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Encyclopedia > Hard disk drive
Hard Disk Drive

An IBM hard disk drive with the metal cover removed. The platters are highly reflective. A screwdriver bit is placed into one of six screws that clamp the stack of platters and spacers. In the center, below the screws and clamping plate, is the motor that spins the platters.
Date Invented: September 13, 1956
Invented By: An IBM team led by Rey Johnson
Connects to:
Market Segments:

A hard disk drive (HDD), commonly referred to as a hard drive, hard disk or fixed disk drive,[1] is a non-volatile storage device which stores digitally encoded data on rapidly rotating platters with magnetic surfaces. Strictly speaking, "drive" refers to a device distinct from its medium, such as a tape drive and its tape, or a floppy disk drive and its floppy disk. Early HDDs had removable media; however, an HDD today is typically a sealed unit (except for a filtered vent hole to equalize air pressure) with fixed media.[2] Image File history File links Hard_disk_platter_reflection. ... is the 256th day of the year (257th in leap years) in the Gregorian calendar. ... A car from 1956 Year 1956 (MCMLVI) was a leap year starting on Sunday (link will display full calendar) of the Gregorian calendar. ... For other uses, see IBM (disambiguation) and Big Blue. ... Reynold Johnson was an American inventor and computer pioneer. ... Fibre Channel Host Bus Adapter (64-bit PCI-X card) SCSI Host Bus Adapter (16-bit ISA card) In computer hardware, a host controller, host adapter, or host bus adapter (HBA) connects a host system (the computer) to other network and storage devices. ... A stylised illustration of a modern personal computer A personal computer (PC) is a computer whose original sales price, size, and capabilities make it useful for individuals. ... A motherboard is the central or primary circuit board making up a complex electronic system, such as a modern computer. ... ATA connector on the left, with two motherboard ATA connectors on the right. ... ATA connector on the left, with two motherboard ATA connectors on the right. ... A SATA power connector. ... 2. ... Scuzzy redirects here. ... In information technology, a server is an application or device that performs services for connected clients as part of a client-server architecture. ... Fibre Channel is a gigabit-speed network technology primarily used for storage networking. ... A Market segment is a subgroup of people or organizations sharing one or more characteristics that cause them to have similar product needs. ... Bold text Desktop computer with several common peripherals (Monitor, keyboard, mouse, speakers, microphone and a printer) A desktop computer is a gay electronic machine computer which convert raw data into meaningful information, made for use on a desk in an office or home and is distinguished from portable computers such... Mobile Computing is a generic term describing your ability to use technology untethered, that is not physically connected, or in remote or mobile (non static) environments. ... Non-volatile storage is a category of computer storage. ... Hard disk platter From Wikipedia, the free encyclopedia. ... In physics, magnetism is a phenomenon by which materials exert an attractive or repulsive force on other materials. ...


A HDD is a rigid-disk drive, although it is probably never referred to as such. By way of comparison, a so-called "floppy" drive (more formally, a diskette drive) has a disc that is flexible. Originally, the term "hard" was temporary slang, substituting "hard" for "rigid", before these drives had an established and universally-agreed-upon name. Some time ago, IBM's internal company term for an HDD was "file".


HDDs (introduced in 1956 as data storage for an IBM accounting computer[3]) were originally developed for use with computers, see History of hard disk drives. It has been suggested that Accounting scholarship be merged into this article or section. ... This article is about the machine. ... The commercial usage of hard disk drives began in 1956 with the shipment of an IBM 305 RAMAC system including a IBM Model 350 disk storage[1]. For many years, hard disk drives were large, cumbersome devices, more suited to use in the protected environment of a data center or...


In the 21st century, applications for HDDs have expanded beyond computers to include digital video recorders, digital audio players, personal digital assistants, digital cameras and video game consoles. In 2005 the first mobile phones to include HDDs were introduced by Samsung and Nokia.[4] The need for large-scale, reliable storage, independent of a particular device, led to the introduction of configurations such as RAID arrays, network attached storage (NAS) systems and storage area network (SAN) systems that provide efficient and reliable access to large volumes of data. Foxtel IQ, a digital video recorder and a satellite cable set-top box. ... Apple iPod nano (third-generation), a best-selling flash-based player An embedded hard drive-based player (Creative ZEN Vision:M) An MP3 CD player (Philips Expanium) More commonly referred to as an MP3 player, a digital audio player (DAP) is a portable consumer electronics device that stores, organizes and... User with Treo (PDA with smartphone functionality) Personal digital assistants (PDAs) are handheld computers, but have become much more versatile over the years. ... Look up digital camera in Wiktionary, the free dictionary. ... Game console redirects here. ... Samsung Electronics (SEC, Hangul:삼성전자; KRXS: 005930, KRXS: 005935, LSE: SMSN, LSE: SMSD) is the worlds largest electronics and information technology company[1], headquartered in Suwon, South Korea. ... This article is about the telecommunications corporation. ... For other uses, see Raid. ... Network-attached storage (NAS) systems are generally computing-storage devices that can be accessed over a computer network, rather than directly being connected to the computer (via a computer bus). ... In computing, a storage area network (SAN) is an architecture to attach remote computer storage devices such as disk array controllers, tape libraries and CD arrays to servers in such a way that to the operating system the devices appear as locally attached devices. ...

Contents

Technology

HDDs record data by magnetizing ferromagnetic material directionally, to represent either a 0 or a 1 binary digit. They read the data back by detecting the magnetization of the material. A typical HDD design consists of a spindle which holds one or more flat circular disks called platters, onto which the data is recorded. The platters are made from a non-magnetic material, usually aluminum alloy or glass, and are coated with a thin layer of magnetic material. Older disks used iron(III) oxide as the magnetic material, but current disks use a cobalt-based alloy. Image File history File links Hard_drive. ... Image File history File links Hard_drive. ... Ferromagnetism is the phenomenon by which materials, such as iron, in an external magnetic field become magnetized and remain magnetized for a period after the material is no longer in the field. ... This article is about the unit of information, see Bit (disambiguation) for other meanings. ... Close-up of a hard disk head resting on the disk platter. ... Iron(III) oxide — also known as ferric oxide, Hematite, red iron oxide, synthetic maghemite, colcothar, or simply rust — is one of the several oxide compounds of iron, and has paramagnetic properties. ... For other uses, see Cobalt (disambiguation). ...

A cross section of the magnetic surface in action. In this case the binary data is encoded using frequency modulation:

The platters are spun at very high speeds (details follow). Information is written to a platter as it rotates past devices called read-and-write heads that operate very close (tens of nanometers in new drives) over the magnetic surface. The read-and-write head is used to detect and modify the magnetization of the material immediately under it. There is one head for each magnetic platter surface on the spindle, mounted on a common arm. An actuator arm (or access arm) moves the heads on an arc (roughly radially) across the platters as they spin, allowing each head to access almost the entire surface of the platter as it spins. The arm is moved using a voice coil actuator or (in older designs) a stepper motor. Stepper motors were outside the head-disk chamber, and preceded voice-coil drives. The latter, for a while, had a structure similar to that of a loudspeaker; the coil and heads moved in a straight line, along a radius of the platters. The present-day structure differs in several respects from that of the earlier voice-coil drives, but the same interaction between the coil and magnetic field still applies, and the term is still used. Image File history File links MagneticMedia. ... Image File history File links MagneticMedia. ... In telecommunications, frequency modulation (FM) conveys information over a carrier wave by varying its frequency. ... Microphotograph of a hard disk head. ... A voice coil is the coil of wire attached to the apex of the moving cone of a loudspeaker. ... Because of induction of the windings, power requirements, and temperature management some glue circuitry is necessary between digital controller and motor. ...


Older drives read the data on the platter by sensing the rate of change of the magnetism in the head; these heads had small coils, and worked (in principle) much like magnetic-tape playback heads, although not in contact with the recording surface. As data density increased, read heads using magnetoresistance (MR) came into use; the electrical resistance of the head changed according to the strength of the magnetism from the platter. Later development made use of spintronics; in these heads, the magnetoresistive effect was much greater that in earlier types, and was dubbed "giant" magnetoresistance (GMR). This refers to the degree of effect, not the physical size, of the head — the heads themselves are extremely tiny, and are too small to be seen without a microscope. GMR read heads are now commonplace.[citation needed] Unsolved problems in physics: Is it possible to construct a practical electronic device that operates on the spin of the electron, rather than its charge? Spintronics (a neologism for spin-based electronics), also known as magnetoelectronics, is an emergent technology which exploits the quantum spin states of electrons as well...


HD heads are kept from contacting the platter surface by the air that is extremely close to the platter; that air moves at, or close to, the platter speed.[citation needed] The record and playback head are mounted on a block called a slider, and the surface next to the platter is shaped to keep it just barely out of contact. It's a type of air bearing.


The magnetic surface of each platter is conceptually divided into many small sub-micrometre-sized magnetic regions, each of which is used to encode a single binary unit of information. In today's HDDs, each of these magnetic regions is composed of a few hundred magnetic grains. Each magnetic region forms a magnetic dipole which generates a highly localized magnetic field nearby. The write head magnetizes a region by generating a strong local magnetic field. Early HDDs used an electromagnet both to generate this field and to read the data by using electromagnetic induction. Later versions of inductive heads included metal in Gap (MIG) heads and thin film heads. In today's heads, the read and write elements are separate, but in close proximity, on the head portion of an actuator arm. The read element is typically magneto-resistive while the write element is typically thin-film inductive.[5] A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ... This article is about the electromagnetic phenomenon. ... For the indie-pop band, see The Magnetic Fields. ... An electromagnet is a type of magnet in which the magnetic field is produced by the flow of an electric current. ... For magnetic induction, see Magnetic field. ... Thin films are material layers of about 1 µm thickness. ... The Giant Magnetoresistive Effect (GMR) is a quantum mechanical effect observed in thin film structures composed of alternating ferromagnetic and nonmagnetic layers. ...


In modern drives, the small size of the magnetic regions creates the danger that their magnetic state might be lost because of thermal effects. To counter this, the platters are coated with two parallel magnetic layers, separated by a 3-atom-thick layer of the non-magnetic element ruthenium, and the two layers are magnetized in opposite orientation, thus reinforcing each other.[6] Another technology used to overcome thermal effects to allow greater recording densities is perpendicular recording, which has been used in many hard drives as of 2007[7][8][9]. General Name, Symbol, Number Ruthenium, Ru, 44 Chemical series transition metals Group, Period, Block 8, 5, d Appearance silvery white metallic Atomic mass 101. ... Perpendicular recording (or Perpendicular Magnetic Recording, PMR) is a recently implemented technology for data recording on hard disk. ...


See File System for how operating systems access data on HDDs and other storage devices. For library and office filing systems, see Library classification. ...


Architecture

A hard disk drive with the platters and spindle motor hub removed showing the copper colored motor coils surrounding a bearing at the center of the spindle motor.

The motor has an external rotor; the stator windings are copper-colored. The spindle bearing is in the center. To the left of center is the actuator with a read-write head under the tip of its very end (near center); the orange stripe along the side of the arm, a thin printed-circuit cable, connects the read-write head to the hub of the actuator. The flexible, somewhat 'U'-shaped, ribbon cable barely visible below and to the left of the actuator arm is the flexible section, one end on the hub, that continues the connection from the head to the controller board on the opposite side. Download high resolution version (1024x717, 141 KB)A dismantled 10GB Quantum Fireball hard drive Date: 28th July 2004 22:51 Camera: Canon DIGITAL IXUS II Exposure: 1/8 sec. ... Download high resolution version (1024x717, 141 KB)A dismantled 10GB Quantum Fireball hard drive Date: 28th July 2004 22:51 Camera: Canon DIGITAL IXUS II Exposure: 1/8 sec. ...


The head support arm is very light, but also rigid; in modern drives, acceleration at the head reaches 250 g's. The term g force or gee force refers to the symbol g, the force of acceleration due to gravity at the earths surface. ...


The silver-colored structure at the upper left is the top plate of the permanent-magnet and moving coil "motor" that swings the heads to the desired position. Beneath this plate is the moving coil, attached to the actuator hub, and beneath that is a thin neodymium-iron-boron (NIB) high-flux magnet. That magnet is mounted on the bottom plate of the "motor".


The coil, itself, is shaped rather like an arrowhead, and made of doubly-coated copper magnet wire. The inner layer is insulation, and the outer is thermoplastic, which bonds the coil together after it's wound on a form, making it self-supporting. Much of the coil, sides of the arrowhead, which points to the actuator bearing center, interacts with the magnetic field to develop a tangential force to rotate the actuator. Considering that current flows (at a given time) radially outward along one side of the arrowhead, and radially inward on the other, the surface of the magnet is half N pole, half S pole; the dividing line is midway, and radial.


Capacity and access speed

PC hard disk drive capacity (in GB). The vertical axis is logarithmic, so the fit line corresponds to exponential growth.

Using rigid disks and sealing the unit allows much tighter tolerances than in a floppy disk drive. Consequently, hard disk drives can store much more data than floppy disk drives and can access and transmit it faster. As of January 2008: Image File history File links Hard_drive_capacity_over_time. ... Image File history File links Hard_drive_capacity_over_time. ... A stylised illustration of a modern personal computer A personal computer (PC) is a computer whose original sales price, size, and capabilities make it useful for individuals. ... A gigabyte (symbol GB) is a unit of measurement in computers of one thousand million bytes (the same as one billion bytes in the short scale usage). ... A logarithmic scale is a scale of measurement that uses the logarithm of a physical quantity instead of the quantity itself. ... In mathematics, exponential growth (or geometric growth) occurs when the growth rate of a function is always proportional to the functions current size. ... A floppy disk is a data storage device that is composed of a disk of thin, flexible (floppy) magnetic storage medium encased in a square or rectangular plastic shell. ...

  • A typical desktop HDD, might store between 120 and 300 GB of data (based on US market data[10]), rotate at 7,200 revolutions per minute (RPM) and have a media transfer rate of 1 Gbit/s or higher. (1 GB = 109 B; 1 Gbit/s = 109 bit/s)
  • The highest capacity HDDs are 1 TB[11].
  • The fastest “enterprise” HDDs spin at 10,000 or 15,000 rpm, and can achieve sequential media transfer speeds above 1.6 Gbit/s.[12] Drives running at 10,000 or 15,000 rpm use smaller platters because of air drag and therefore generally have lower capacity than the highest capacity desktop drives.
  • Mobile, i.e., laptop HDDs, which are physically smaller than their desktop and enterprise counterparts, tend to be slower and have less capacity. A typical mobile HDD spins at 5,400 rpm, with 7,200 rpm models available for a slight price premium. Because of the smaller disks, mobile HDDs generally have lower capacity than the highest capacity desktop drives.

The exponential increases in disk space and data access speeds of HDDs have enabled the commercial viability of consumer products that require large storage capacities, such as digital video recorders and digital audio players.[13] In addition, the availability of vast amounts of cheap storage has made viable a variety of web-based services with extraordinary capacity requirements, such as free-of-charge web search and email (Google, Yahoo!, etc.). Look up desktop in Wiktionary, the free dictionary. ... This article is about the unit of measurement. ... For other uses, see Revolutions per minute (disambiguation). ... This article is about a measurement term for data storage capacity. ... For the band, see Laptop (band). ... Foxtel IQ, a digital video recorder and a satellite cable set-top box. ... Apple iPod nano (third-generation), a best-selling flash-based player An embedded hard drive-based player (Creative ZEN Vision:M) An MP3 CD player (Philips Expanium) More commonly referred to as an MP3 player, a digital audio player (DAP) is a portable consumer electronics device that stores, organizes and... This article is about the corporation. ... Yahoo redirects here. ...


The main way to decrease access time is to increase rotational speed, while the main way to increase throughput and storage capacity is to increase areal density. A vice president of Seagate Technology projects a future growth in disk density of 40% per year.[14] Access times have not kept up with throughput increases, which themselves have not kept up with growth in storage capacity. Seagate Technology (NYSE: STX) is a major American manufacturer of hard drives, founded in 1979 and based in Scotts Valley, California. ... In telecommunication, the term access time has the following meanings: In a telecommunication system, the elapsed time between the start of an access attempt and successful access. ...


As of 2006, some disk drives use perpendicular recording technology to increase recording density and throughput.[15] Perpendicular recording (or Perpendicular Magnetic Recording, PMR) is a recently implemented technology for data recording on hard disk. ...


The first 3.5" HDD marketed as able to store 1 TB was the Hitachi Deskstar 7K1000. It contains five platters at approximately 200 GB each, providing 935.5 GiB of usable space.[16] Hitachi has since been joined by Samsung (Samsung SpinPoint F1, which has 3 × 334 GB platters), Seagate and Western Digital in the 1 TB drive market.[17][18] The Deskstar is the name of a product line of computer hard drives. ...

Form factor Width Largest capacity Platters (Max)
5.25" FH 146 mm 47 GB[19] (1998) 14
5.25" HH 146 mm 19.3 GB[20] (1998) 4[21]
3.5" 102 mm 1 TB[16] (2007) 5
2.5" 69.9 mm 500 GB[22] (2008) 3
1.8" (PCMCIA) 54 mm 160 GB[23] (2007)
1.8" (ATA-7 LIF) 53.8 mm
1.3" 36.4 mm 40 GB[24] (2008) 1

Full-height, 2 half-height, and 3. ... A millimetre (American spelling: millimeter), symbol mm is an SI unit of length that is equal to one thousandth of a metre. ... This article is about the unit of measurement. ... Full-height, 2 half-height, and 3. ... This article is about a measurement term for data storage capacity. ... Portable Computer Cards (PC cards) are interchangeable peripherals designed to be inserted into laptop computers in order to enable extra hardware functions. ... Low-infortion sockets (LIF) are literally IC sockets specially designed so the insertion force is low. ...

Capacity measurements

A disassembled and labeled 1997 hard drive.

The capacity of an HDD can be calculated by multiplying the number of cylinders by the number of heads by the number of sectors by the number of bytes/sector (most commonly 512). Drives with ATA interface bigger and more than eight gigabytes behave as if they were structured into 16383 cylinders, 16 heads, and 63 sectors, for compatibility with older operating systems. Unlike in the 1980s, the cylinder, head, sector (C/H/S) counts reported to the CPU by a modern ATA drive are no longer actual physical parameters since the reported numbers are constrained by historic operating-system interfaces and with zone bit recording the actual number of sectors varies by zone. Disks with SCSI interface address each sector with a unique integer number; the operating system remains ignorant of their head or cylinder count. Image File history File links Size of this preview: 800 × 501 pixelsFull resolution (5071 × 3173 pixel, file size: 4. ... Image File history File links Size of this preview: 800 × 501 pixelsFull resolution (5071 × 3173 pixel, file size: 4. ... A cylinder in computer terms is related to disk storage technology: Hard disk cylinder used in Windows and Unix galaxies Cylinder (hard disk) Another term for tracks Cylinder-head-sector CKD disk cylinder used in mainframe galaxy (Cylinder (disk drive)) Categories: | ... It has been suggested that Disk sector be merged into this article or section. ... ATA connector on the left, with two motherboard ATA connectors on the right. ... Zone Bit Recording (ZBR) is used by disk drives to store more sectors per track on outer tracks than on inner tracks. ... Scuzzy redirects here. ...


The old C/H/S scheme has been replaced by logical block addressing. In some cases, to try to "force-fit" the C/H/S scheme to large-capacity drives, the number of heads was given as 64, although no drive has anywhere near 32 platters. Logical block addressing (LBA) is a common scheme used for specifying the location of blocks of data stored on computer storage devices, generally secondary storage systems such as hard disks. ...


Hard disk drive manufacturers specify disk capacity using the SI prefixes mega-, giga- and tera-, and their abbreviations M, G and T. Byte is typically abbreviated B. An SI prefix (also known as a metric prefix) is a name or associated symbol that precedes a unit of measure (or its symbol) to form a decimal multiple or submultiple. ... Mega (symbol M) is a SI prefix in the SI system of units denoting a factor of 106, i. ... Look up giga- in Wiktionary, the free dictionary. ... Tera (symbol: T) is a prefix in the SI system of units denoting 1012, or 1 000 000 000 000. ...


Most operating-system tools report capacity using the same abbreviations but actually use binary prefixes. For instance, the prefix mega-, which normally means 106 (1,000,000), in the context of data storage can mean 220 (1,048,576), which is nearly 5% more. Similar usage has been applied to prefixes of greater magnitude. This results in a discrepancy between the disk manufacturer's stated capacity and the apparent capacity of the drive when examined through most operating-system tools. The difference becomes even more noticeable (7%) for a gigabyte. For example, Microsoft Windows reports disk capacity both in decimal-based units to 12 or more significant digits and with binary-based units to three significant digits. Thus a disk specified by a disk manufacturer as a 30 GB disk might have its capacity reported by Windows 2000 both as "30,065,098,568 bytes" and "28.0 GB". The disk manufacturer used the SI definition of "giga", 109 to arrive at 30 GB; however, because the utilities provided by Windows, Mac and some Linux distributions define a gigabyte as 1,073,741,824 bytes (230 bytes, often referred to as a gibibyte, or GiB), the operating system reports capacity of the disk drive as (only) 28.0 GB. // In computing, binary prefixes can be used to quantify large numbers where powers of two are more useful than powers of ten (such as computer memory sizes). ... Mega (symbol M) is a SI prefix in the SI system of units denoting a factor of 106, i. ... Windows redirects here. ... Look up si, Si, SI in Wiktionary, the free dictionary. ... A gibibyte is a unit of information or computer storage. ...


Form factors

5¼" full height 110 MB HDD,
2½" 8.5 mm 6495 MB HDD,
US/UK pennies for comparison
Six hard drives with 8", 5.25", 3.5", 2.5", 1.8", and 1" disks, partially disassembled to show platters and read-write heads, with a ruler showing inches.

The earliest “form factor” hard disk drives inherited their dimensions from floppy-disk drives (FDDs), so that either could be mounted in chassis slots, and thus the HDD form factors became colloquially named after the corresponding FDD types. "Form factor" compatibility continued after the 3½ in size even though floppy disk drives with new smaller dimensions ceased to be offered. Image File history File linksMetadata 5. ... Image File history File linksMetadata 5. ... A floppy disk is a data storage device that is composed of a disk of thin, flexible (floppy) magnetic storage medium encased in a square or rectangular plastic shell. ...

  • "8 inch" drive: (9.5 in x 4.624 in x 14.25 in = 241.3 mm x 117.5 mm x 362 mm)
    In 1979, Shugart Associates' SA1000 was the first form factor compatible HDD, having the same dimensions and a compatible interface to the 8" FDD. Both "full height" and "half height" (2.313 in) versions were available.
  • "5¼ inch" drive: (5.75 in x 1.63 in x 8 in = 146.1 mm x 41.4 mm x 203 mm)
    This smaller form factor, first used in an HDD by Seagate in 1980, was the same size as full height 5¼-inch diameter FDD, i.e., 3.25 inches high. This is twice as high as commonly used today; i.e., 1.63 in = 41.4 mm (“half height”). Most desktop models of drives for optical 120 mm disks (DVD, CD) use the half height 5¼" dimension, but it fell out of fashion for HDDs. The Quantum “Bigfoot” HDD was the last to use it in the late 1990s, with “low-profile” (~25 mm) and “ultra-low-profile” (~20 mm) high versions.
  • "3½ inch" drive: (4 in x 1 in x 5.75 in = 101.6 mm x 25.4 mm x 146 mm)
    This smaller form factor, first used in an HDD by Rodime in 1984, was the same size as the "half height" 3½ FDD, i.e., 1.63 inches high. Today has been largely superseded by 1-inch high “slimline” or “low-profile” versions of this form factor which is used by most desktop HDDs.
  • "2½ inch" drive: (2.75 in x 0.374 in x 3.945 in = 69.85 mm x 9.5 mm x 100 mm)
    This smaller form factor was introduced by PrairieTek in 1988; there is no corresponding FDD. It is widely used today for hard-disk drives in mobile devices (laptops, music players, etc.). Today, the dominant height of this form factor is 9.5 mm, but there were also 19 mm, 17 mm, and 12.5 mm high variants in use.
  • "1.8 inch" drive: (54 mm × 8 mm × 71 mm)
    This form factor, originally introduced by Integral Peripherals in 1993, has evolved into the ATA-7 LIF with dimensions as stated. It is increasingly used in digital audio players and subnotebooks. An original variant exists for 2–5 GB sized HDDs that fit directly into a PC card expansion slot.
  • "1 inch" drive: (42.8 mm × 5 mm × 36.4 mm)
    This form factor was introduced in 1999 as IBM's Microdrive to fit inside a CF Type II slot. Samsung calls the same form factor "1.3 inch" drive in its product literature.[25]
  • "0.85 inch" drive: (24 mm × 5 mm × 32 mm)
    Toshiba announced this form factor in January 2004[26] for use in mobile phones and similar applications, including SD/MMC slot compatible HDDs optimized for video storage on 4G handsets. Toshiba currently sells a 4 GB (MK4001MTD) and 8 GB (MK8003MTD) version[4] and holds the Guinness World Record for the smallest harddisk drive.[27]

Major manufacturers discontinued the development of new products for the 1-inch (=1.3-inch) and 0.85-inch form factors in 2007, due to falling prices of flash memory[28], although Samsung introduced in 2008 with the SpinPoint A1 another 1.3-inch drive. Shugart Associates was a computer peripheral manufacturer, famous for introducing the floppy disk to the microcomputer market. ... DVD (also known as Digital Versatile Disc or Digital Video Disc) is a popular optical disc storage media format. ... CD may stand for: Compact Disc Canadian Forces Decoration Cash Dispenser (at least used in Japan) CD LPMud Driver Centrum-Demokraterne (Centre Democrats of Denmark) Certificate of Deposit České Dráhy (Czech Railways) Chad (NATO country code) Chalmers Datorförening (computer club of the Chalmers University of Technology) a 1960s... Apple iPod nano (third-generation), a best-selling flash-based player An embedded hard drive-based player (Creative ZEN Vision:M) An MP3 CD player (Philips Expanium) More commonly referred to as an MP3 player, a digital audio player (DAP) is a portable consumer electronics device that stores, organizes and... Sony VAIO model C1 subnotebook A subnotebook is a small and lightweight portable computer, with most of the features of a standard notebook computer but smaller. ... The PCMCIA is the Personal Computer Memory Card International Association, an industry trade association that creates standards for notebook computer peripheral devices. ... For other uses, see IBM (disambiguation) and Big Blue. ... For other uses, see Microdrive (disambiguation). ... CompactFlash (CF) was originally a type of data storage device, used in portable electronic devices. ... Toshiba Corporations headquarters (Center) in Hamamatsucho, Tokyo Toshiba Corporation sales by division for year ending March 31, 2005 Toshiba Corporation ) (TYO: 6502 ) is a Japanese multinational conglomerate manufacturing company, headquartered in Tokyo, Japan. ... A SanDisk Multi Card Reader, with a 2 GB SD Card inserted. ... A 32 MB MultiMediaCard MultiMediaCard A 128 MB RS-MMC card and an adapter An RS-MMC card with adapter attached The MultiMediaCard (MMC) is a flash memory memory card standard. ... This article is about the mobile phone standard. ... The Guinness Book of Records (or in recent editions Guinness World Records, and in previous US editions Guinness Book of World Records) is a book published annually, containing an internationally recognized collection of superlatives: both in terms of human achievement and the extrema of the natural world. ...


The inch-based nickname of all these form factors usually do not indicate any actual product dimension (which are for more recent form factors specified in millimeters), but just roughly indicate a size relative to disk diameters, in the interest of historic continuity.


Other characteristics

Capacity of a hard disk drive is usually quoted in gigabytes. Older HDDs quoted their smaller capacities in megabytes. This article is about the unit of measurement. ... This article is about a unit of data measurement. ...


The data transfer rate at the inner zone ranges from 44.2 MB/s to 74.5 MB/s, while the transfer rate at the outer zone ranges from 74.0 MB/s to 111.4 MB/s. An HDD's random access time ranges from 5 ms to 15 ms. MB, Mb, mB or mb may mean: Mb (digraph) Megabit (1,000,000 bits) or mebibit (220 = 1,048,576 bits); the preferred symbols are Mb and Mibit, respectively¹ Megabyte (1,000,000 bytes) or mebibyte (220 = 1,048,576 bytes); the preferred symbols are MB and MiB, respectively¹ MB... Look up MS, Ms, ms, .ms in Wiktionary, the free dictionary. ...


Access and interfaces

Hard disk drives are accessed over one of a number of bus types, including parallel ATA (PATA, also called IDE or EIDE), Serial ATA (SATA), SCSI, Serial Attached SCSI (SAS), and Fibre Channel. Bridge circuitry is sometimes used to connect hard disk drives to buses that they cannot communicate with natively, such as IEEE 1394 and USB. ATA cables: 40 wire ribbon cable top, 80 wire ribbon cable bottom Advanced Technology Attachment (ATA) is a standard interface for connecting storage devices such as hard disks and CD-ROM drives inside personal computers. ... County Møre og Romsdal Landscape Nordmøre Municipality NO-1551 Administrative centre Eide Mayor (2003) Arnfinn Storvik (H) Official language form BokmÃ¥l Area  - Total  - Land  - Percentage Ranked 356 152 km² 146 km² 0. ... SATA redirects here. ... Scuzzy redirects here. ... 2. ... Fibre Channel is a gigabit-speed network technology primarily used for storage networking. ... A 6-Pin Firewire 400 connector FireWire (also known as i. ... USB redirects here. ...


Back in the days of the ST-506 interface, the data encoding scheme was also important. The first ST-506 disks used Modified Frequency Modulation (MFM) encoding, and transferred data at a rate of 5 megabits per second. Later on, controllers using 2,7 RLL (or just "RLL") encoding increased the transfer rate by 50%, to 7.5 megabits per second; this also increased disk capacity by fifty percent. The ST-506 was the first hard disk intended for use specifically on microcomputers, introduced in 1980 by Seagate Technology. ... An encoder is a device used to encode a signal (such as a bitstream) or data into a form that is acceptable for transmission or storage. ... Modified Frequency Modulation, commonly MFM, is a line coding scheme used to encode information on most floppy disk formats, which include the floppy disk formats used in most CP/M machines as well as PCs running DOS. MFM is a modification to the original FM (frequency modulation) scheme for encoding... The Megabit is a unit of information storage, abbreviated Mbit or sometimes Mb. ... Run Length Limited codes, or RLL codes are widely used in hard disk drives (and notably digital optical discs, such as CD, DVD and BluRay disc) to prevent long stretches of no transitions, and therefore decoding uncertainty, from creeping in. ...


Many ST-506 interface disk drives were only specified by the manufacturer to run at the lower MFM data rate, while other models (usually more expensive versions of the same basic disk drive) were specified to run at the higher RLL data rate. In some cases, a disk drive had sufficient margin to allow the MFM specified model to run at the faster RLL data rate; however, this was often unreliable and was not recommended. (An RLL-certified disk drive could run on a MFM controller, but with 1/3 less data capacity and speed.)


Enhanced Small Disk Interface (ESDI) also supported multiple data rates (ESDI disks always used 2,7 RLL, but at 10, 15 or 20 megabits per second), but this was usually negotiated automatically by the disk drive and controller; most of the time, however, 15 or 20 megabit ESDI disk drives weren't downward compatible (i.e. a 15 or 20 megabit disk drive wouldn't run on a 10 megabit controller). ESDI disk drives typically also had jumpers to set the number of sectors per track and (in some cases) sector size. Enhanced Small Disk Interface (ESDI) was a disc interface designed by Maxtor Corporation in the early 1980s to be a follow-on to the ST-506 interface. ...


SCSI originally had just one speed, 5 MHz (for a maximum data rate of five megabytes per second), but later this was increased dramatically. The SCSI bus speed had no bearing on the disk's internal speed because of buffering between the SCSI bus and the disk drive's internal data bus; however, many early disk drives had very small buffers, and thus had to be reformatted to a different interleave (just like ST-506 disks) when used on slow computers, such as early IBM PC compatibles and early Apple Macintoshes. IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC, XT, or AT internal design, facilitated by various manufacturers... The first Macintosh computer, introduced in 1984, upgraded to a 512K Fat Mac. The Macintosh or Mac, is a line of personal computers designed, developed, manufactured, and marketed by Apple Computer. ...


ATA disks have typically had no problems with interleave or data rate, due to their controller design, but many early models were incompatible with each other and couldn't run in a master/slave setup (two disks on the same cable). This was mostly remedied by the mid-1990s, when ATA's specification was standardised and the details began to be cleaned up, but still causes problems occasionally (especially with CD-ROM and DVD-ROM disks, and when mixing Ultra DMA and non-UDMA devices). ATA cables: 40 wire ribbon cable top, 80 wire ribbon cable bottom Advanced Technology Attachment (ATA) is a standard interface for connecting storage devices such as hard disks and CD-ROM drives inside personal computers. ...


Serial ATA does away with master/slave setups entirely, placing each disk on its own channel (with its own set of I/O ports) instead.


FireWire/IEEE 1394 and USB(1.0/2.0) HDDs are external units containing generally ATA or SCSI disks with ports on the back allowing very simple and effective expansion and mobility. Most FireWire/IEEE 1394 models are able to daisy-chain in order to continue adding peripherals without requiring additional ports on the computer itself. The elementary meaning of daisy chain is a garland created from the daisy flower, generally as a childrens game. ...


Disk interface families used in personal computers

Notable families of disk interfaces include:

  • Historical bit serial interfaces — connected to a hard disk drive controller with three cables, one for data, one for control and one for power. The HDD controller provided significant functions such as serial to parallel conversion, data separation and track formatting, and required matching to the drive in order to assure reliability.
    • ST506 used MFM (Modified Frequency Modulation) for the data encoding method.
    • ST412 was available in either MFM or RLL (Run Length Limited) variants.
    • Enhanced Small Disk Interface (ESDI) was an interface developed by Maxtor to allow faster communication between the PC and the disk than MFM or RLL.
  • Modern bit serial interfaces — connect to a host bus adapter (today typically integrated into the "south bridge") with two cables, one for data/control and one for power.
    • Fibre Channel (FC), is a successor to parallel SCSI interface on enterprise market. It is a serial protocol. In disk drives usually the Fibre Channel Arbitrated Loop (FC-AL) connection topology is used. FC has much broader usage than mere disk interfaces, it is the cornerstone of storage area networks (SANs). Recently other protocols for this field, like iSCSI and ATA over Ethernet have been developed as well. Confusingly, drives usually use copper twisted-pair cables for Fibre Channel, not fibre optics. The latter are traditionally reserved for larger devices, such as servers or disk array controllers.
    • Serial ATA (SATA). The SATA data cable has one data pair for differential transmission of data to the device, and one pair for differential receiving from the device, just like EIA-422. That requires that data be transmitted serially. The same differential signaling system is used in RS485, LocalTalk, USB, Firewire, and differential SCSI.
    • Serial Attached SCSI (SAS). The SAS is a new generation serial communication protocol for devices designed to allow for much higher speed data transfers and is compatible with SATA. SAS uses serial communication instead of the parallel method found in traditional SCSI devices but still uses SCSI commands.
  • Word serial interfaces — connect to a host bus adapter (today typically integrated into the "south bridge") with two cables, one for data/control and one for power. The earliest versions of these interfaces typically had a 16 bit parallel data transfer to/from the drive and there are 8 and 32 bit variants. Modern versions have serial data transfer. The word nature of data transfer makes the design of a host bus adapter significantly simpler than that of the precursor HDD controller.
    • Integrated Drive Electronics (IDE), later renamed to ATA, and then later to PATA ("parallel ATA", to distinguish it from the new Serial ATA). The original name reflected the innovative integration of HDD controller with HDD itself, which was not found in earlier disks. Moving the HDD controller from the interface card to the disk drive helped to standardize interfaces, including reducing the cost and complexity. The 40 pin IDE/ATA connection of PATA transfers 16 bits of data at a time on the data cable. The data cable was originally 40 conductor, but later higher speed requirements for data transfer to and from the hard drive led to an "ultra DMA" mode, known as UDMA, which required an 80 conductor variant of the same cable; the other conductors provided the grounding necessary for enhanced high-speed signal quality. The interface for 80 pin only has 39 pins, the missing pin acting as a key to prevent incorrect insertion of the connector to an incompatible socket, a common cause of disk and controller damage.
    • EIDE was an unofficial update (by Western Digital) to the original IDE standard, with the key improvement being the use of direct memory access (DMA) to transfer data between the disk and the computer without the involvement of the CPU, an improvement later adopted by the official ATA standards. By directly transferring data between memory and disk, DMA does not require the CPU/program/operating system to leave other tasks idle while the data transfer occurs.
    • Small Computer System Interface (SCSI), originally named SASI for Shugart Associates System Interface, was an early competitor of ESDI. SCSI disks were standard on servers, workstations, and Apple Macintosh computers through the mid-90s, by which time most models had been transitioned to IDE (and later, SATA) family disks. Only in 2005 did the capacity of SCSI disks fall behind IDE disk technology, though the highest-performance disks are still available in SCSI and Fibre Channel only. The length limitations of the data cable allows for external SCSI devices. Originally SCSI data cables used single ended data transmission, but server class SCSI could use differential transmission, either low voltage differential (LVD) or high voltage differential (HVD).
Acronym or abbreviation Meaning Description
SASI Shugart Associates System Interface Historical predecessor to SCSI.
SCSI Small Computer System Interface Bus oriented that handles concurrent operations.
SAS Serial Attached SCSI Improvement of SCSI, uses serial communication instead of parallel.
ST-506 Historical Seagate interface.
ST-412 Historical Seagate interface (minor improvement over ST-506).
ESDI Enhanced Small Disk Interface Historical; backwards compatible with ST-412/506, but faster and more integrated.
ATA Advanced Technology Attachment Successor to ST-412/506/ESDI by integrating the disk controller completely onto the device. Incapable of concurrent operations.
SATA Serial ATA Improvement of ATA, uses serial communication instead of parallel.

Modified Frequency Modulation, commonly MFM, is a line coding scheme used to encode information on most floppy disk formats, which include the floppy disk formats used in most CP/M machines as well as PCs running DOS. MFM is a modification to the original FM (frequency modulation) scheme for encoding... Run Length Limited codes, or RLL codes are widely used in hard disk drives (and notably digital optical discs, such as CD, DVD and BluRay disc) to prevent long stretches of no transitions, and therefore decoding uncertainty, from creeping in. ... Enhanced Small Disk Interface (ESDI) was a disc interface designed by Maxtor Corporation in the early 1980s to be a follow-on to the ST-506 interface. ... This article does not cite any references or sources. ... Fibre Channel is a gigabit-speed network technology primarily used for storage networking. ... Arbitrated Loop is a Fibre Channel topology that requires no fibre channel switches. ... In computing, a storage area network (SAN) is an architecture to attach remote computer storage devices such as disk array controllers, tape libraries and CD arrays to servers in such a way that to the operating system the devices appear as locally attached devices. ... iSCSI is a protocol that allows clients (called initiators) to send SCSI commands (CDBs) to SCSI storage devices (targets) on remote servers. ... ATA over Ethernet (AoE) is a network protocol developed by Coraid, Inc. ... In computing, a disk array controller is a computer hardware device which provides secondary storage services to computer systems, often in large servers. ... SATA redirects here. ... EIA-422 (formerly RS-422), now TIA-422, is a technical standard which specifies the electrical characteristics of the balanced voltage digital interface circuit[1]. It provides for data transmission, using balanced or differential signaling, with unidirectional/non-reversible, terminated or non-terminated transmission lines, point to point, or multi... It has been suggested that this article or section be merged into Low voltage differential signaling. ... EIA-485 (formerly RS-485 or RS485) is an OSI Model physical layer electrical specification of a two-wire, half-duplex, multipoint serial connection. ... LocalTalk is a particular implementation of the physical layer of the AppleTalk networking system from Apple Computer. ... Note: USB may also mean upper sideband in radio. ... The 6-pin and 4-pin FireWire 400 Connectors The alternative ethernet-style cabling used by 1394c FireWire is Apple Inc. ... Scuzzy redirects here. ... 2. ... This article does not cite any references or sources. ... ATA cables: 40 wire ribbon cable top, 80 wire ribbon cable bottom Advanced Technology Attachment (ATA), is a standard interface for connecting storage devices such as hard disks and CD-ROM drives inside personal computers. ... SATA redirects here. ... It has been suggested that Ground conductor be merged into this article or section. ... Direct memory access (DMA) is a feature of modern computers that allows certain hardware subsystems within the computer to access system memory for reading and/or writing independently of the central processing unit. ... CPU can stand for: in computing: Central processing unit in journalism: Commonwealth Press Union in law enforcement: Crime prevention unit in software: Critical patch update, a type of software patch distributed by Oracle Corporation in Macleans College is often known as Ash Lim. ... SCSI stands for Small Computer System Interface, and is a standard interface for transferring data between devices on a computer bus. ... The first Macintosh computer, introduced in 1984, upgraded to a 512K Fat Mac. The Macintosh or Mac, is a line of personal computers designed, developed, manufactured, and marketed by Apple Computer. ... It has been suggested that this article or section be merged with Backronym and Apronym (Discuss) Acronyms and initialisms are abbreviations, such as NATO, laser, and ABC, written as the initial letter or letters of words, and pronounced on the basis of this abbreviated written form. ... SASI is an acronym for the Shugart Associates System Interface, the ancestor of SCSI (Small Computer System Interface). ... Scuzzy redirects here. ... In computer architecture, a bus is a subsystem that transfers data or power between computer components inside a computer or between computers and typically is controlled by device driver software. ... Parallel programming (also concurrent programming), is a computer programming technique that provides for the execution of operations concurrently, either within a single computer, or across a number of systems. ... 2. ... The ST-506 was the first hard disk intended for use specifically on microcomputers, introduced in 1980 by Seagate Technology. ... This does not cite its references or sources. ... Enhanced Small Disk Interface (ESDI) was a disc interface designed by Maxtor Corporation in the early 1980s to be a follow-on to the ST-506 interface. ... ATA cables: 40 wire ribbon cable top, 80 wire ribbon cable bottom Advanced Technology Attachment (ATA) is a standard interface for connecting storage devices such as hard disks and CD-ROM drives inside personal computers. ... A successor function is the label in the literature for what is actually an operation. ... SATA redirects here. ...

Integrity

An IBM HDD head resting on a disk platter. Since the drive is not in operation, the head is simply pressed against the disk by the suspension. The orange color is not typical of modern drives, which are typically silvery.
Close-up of a hard disk head resting on a disk platter, and its suspension. A reflection of the head and suspension are visible beneath on the mirror-like disk.

Due to the extremely close spacing between the heads and the disk surface, any contamination of the read-write heads or platters can lead to a head crash — a failure of the disk in which the head scrapes across the platter surface, often grinding away the thin magnetic film and causing data loss. Head crashes can be caused by electronic failure, a sudden power failure, physical shock, wear and tear, corrosion, or poorly manufactured platters and heads. Image File history File links Download high-resolution version (1024x725, 286 KB) This is a side view of the read head of an IBM hard disk, circa 2002. ... Image File history File links Download high-resolution version (1024x725, 286 KB) This is a side view of the read head of an IBM hard disk, circa 2002. ... Image File history File linksMetadata Download high resolution version (1698x1542, 228 KB) Summary A hard disk drive head resting on the disk platter. ... Image File history File linksMetadata Download high resolution version (1698x1542, 228 KB) Summary A hard disk drive head resting on the disk platter. ... A head crash occurs when the read-write head of a hard disk drive touches its rotating platter. ...


The HDD's spindle system relies on air pressure inside the enclosure to support the heads at their proper flying height while the disk rotates. An HDD requires a certain range of air pressures in order to operate properly. The connection to the external environment and pressure occurs through a small hole in the enclosure (about 0.5 mm in diameter), usually with a carbon filter on the inside (the breather filter, see below). If the air pressure is too low, then there is not enough lift for the flying head, so the head gets too close to the disk, and there is a risk of head crashes and data loss. Specially manufactured sealed and pressurized disks are needed for reliable high-altitude operation, above about 3,000 m (10,000 feet). Note that modern commercial aircraft have a pressurized cabin, whose pressure altitude does not normally exceed 2,600 m(8,500 feet) - thus, ordinary hard drives can safely be used in flight. Modern disks include temperature sensors and adjust their operation to the operating environment. Breather holes can be seen on all disks — they usually have a sticker next to them, warning the user not to cover the holes. The air inside the operating disk is constantly moving too, being swept in motion by friction with the spinning platters. This air passes through an internal recirculation (or "recirc") filter to remove any leftover contaminants from manufacture, any particles or chemicals that may have somehow entered the enclosure, and any particles or outgassing generated internally in normal operation. Very high humidity for extended periods can corrode the heads and platters. Flying machine redirects here. ... Cabin pressurization is the active pumping of air into the cabin of an aircraft to increase the air pressure within the cabin. ... In aviation, pressure altitude is the indicated altitude when an altimeter is set to 1013 hPa (29. ...


For giant magnetoresistive (GMR) heads in particular, a minor head crash from contamination (that does not remove the magnetic surface of the disk) still results in the head temporarily overheating, due to friction with the disk surface, and can render the data unreadable for a short period until the head temperature stabilizes (so called "thermal asperity," a problem which can partially be dealt with by proper electronic filtering of the read signal). Founding results of Fert The Giant Magnetoresistance (GMR) is a quantum mechanical effect observed in thin film structures composed of alternating ferromagnetic and nonmagnetic metal layers. ...


The hard disk's electronics control the movement of the actuator and the rotation of the disk, and perform reads and writes on demand from the disk controller. Modern disk firmware is capable of scheduling reads and writes efficiently on the platter surfaces and remapping sectors of the media which have failed. The disk controller (or hard disk controller) is the circuit which allows the CPU to communicate with a hard disk, floppy disk or other kind of disk drive. ...


Landing zones and load/unload technology

Microphotograph of a hard disk head. The size of the front face (which is the "trailing face" of the slider) is about 0.3 mm × 1.0 mm. The (not visible) bottom face of the slider is about 1.0 mm × 1.25 mm (so called "nano" size) and faces the platter. One functional part of the head is the round, orange structure in the middle - the lithographically defined copper coil of the write transducer. Also note the electric connections by wires bonded to gold-plated pads.

Most HDDs prevent power interruptions from shutting the drive down with its heads landing in the data zone by either moving the heads to a landing zone or unloading (i.e., load/unload) the heads. Image File history File links Download high resolution version (890x598, 59 KB) Summary Microphotograph of a r/w head from a hard disk. ... Image File history File links Download high resolution version (890x598, 59 KB) Summary Microphotograph of a r/w head from a hard disk. ... A micrograph is a photograph or similar image taken through a microscope or similar device to show a magnified image of an item. ... Photolithography is a process used in semiconductor device fabrication to transfer a pattern from a photomask (also called reticle) to the surface of a substrate. ... This article is about transducers in engineering. ...


A landing zone is an area of the platter usually near its inner diameter (ID), where no data is stored. This area is called the Contact Start/Stop (CSS) zone. Disks are designed such that either a spring or, more recently, rotational inertia in the platters is used to park the heads in the case of unexpected power loss. In this case, the spindle motor temporarily acts as a generator, providing power to the actuator. This article is about inertia as it applies to local motion. ...


Spring tension from the head mounting constantly pushes the heads towards the platter. While the disk is spinning, the heads are supported by an air bearing and experience no physical contact or wear. In CSS drives the sliders carrying the head sensors (often also just called heads) are designed to survive a number of landings and takeoffs from the media surface, though wear and tear on these microscopic components eventually takes its toll. Most manufacturers design the sliders to survive 50,000 contact cycles before the chance of damage on startup rises above 50%. However, the decay rate is not linear: when a disk is younger and has had fewer start-stop cycles, it has a better chance of surviving the next startup than an older, higher-mileage disk (as the head literally drags along the disk's surface until the air bearing is established). For example, the Seagate Barracuda 7200.10 series of desktop hard disks are rated to 50,000 start-stop cycles.[29] This means that no failures attributed to the head-platter interface were seen before at least 50,000 start-stop cycles during testing.


Around 1995 IBM pioneered a technology where a landing zone on the disk is made by a precision laser process (Laser Zone Texture = LZT) producing an array of smooth nanometer-scale "bumps" in a landing zone, thus vastly improving stiction and wear performance. This technology is still largely in use today (2007), predominantly in desktop and enterprise (3.5 inch) drives. In general, CSS technology can be prone to increased stiction (the tendency for the heads to stick to the platter surface), e.g. as a consequence of increased humidity. Excessive stiction can cause physical damage to the platter and slider or spindle motor. Stiction is an informal portmanteau of the term static friction (μs), perhaps also influenced by the verb stick. Two solid objects pressing against each other (but not sliding) will require some threshold of force parallel to the surface of contact in order to overcome static cohesion. ...


Load/Unload technology relies on the heads being lifted off the platters into a safe location, thus eliminating the risks of wear and stiction altogether. The first HDD RAMAC and most early disk drives used complex mechanisms to load and unload the heads. Modern HDDs use ramp loading, first introduced by Memorex in 1967[30], to load/unload onto plastic "ramps" near the outer disk edge. RAMAC is an IBM trademark for mass storage products. ...


All HDDs today still use one of these two technologies. Each has a list of advantages and drawbacks in terms of loss of storage area on the disk, relative difficulty of mechanical tolerance control, cost of implementation, etc.


Addressing shock robustness, IBM also created a technology for their ThinkPad line of laptop computers called the Active Protection System. When a sudden, sharp movement is detected by the built-in accelerometer in the Thinkpad, internal hard disk heads automatically unload themselves to reduce the risk of any potential data loss or scratch defects. Apple later also utilized this technology in their PowerBook, iBook, MacBook Pro, and MacBook line, known as the Sudden Motion Sensor. Toshiba has released similar technology in their laptops.[31] For other uses, see IBM (disambiguation) and Big Blue. ... IBM ThinkPad R51 ThinkPad is the brand name for a range of portable laptop and notebook computers originally designed and sold by IBM. Since early 2005 the ThinkPad range has been manufactured and marketed by Lenovo, which purchased the IBM PC division. ... A depiction of an accelerometer designed at Sandia National Laboratories. ... Apple Inc. ... The PowerBook was a line of Macintosh laptop computers that was designed, manufactured and sold by Apple Computer, Inc. ... The original Blueberry iBook Clamshell The iBook is a now discontinued line of laptop computers that was developed and sold by Apple Inc. ... The MacBook Pro is a line of Macintosh notebook computers by Apple for the professional market. ... This article is about the Apple computer called MacBook. For the MacBook family as a whole, see MacBook family. ... The Sudden Motion Sensor is a patent-pending data protection feature introduced by Apple Computer into its refreshed PowerBook and iBook lines on January 1, 2005 and July 26, 2005 respectively. ... Toshiba Corporations headquarters (Center) in Hamamatsucho, Tokyo Toshiba Corporation sales by division for year ending March 31, 2005 Toshiba Corporation ) (TYO: 6502 ) is a Japanese multinational conglomerate manufacturing company, headquartered in Tokyo, Japan. ...


Disk failures and their metrics

Wikibooks has a book on the topic of
Minimizing hard disk drive failure and data loss

Most major hard disk and motherboard vendors now support self-monitoring, analysis and reporting technology (S.M.A.R.T.), which attempts to alert users to impending failures. Image File history File links Wikibooks-logo-en. ... Wikibooks logo Wikibooks, previously called Wikimedia Free Textbook Project and Wikimedia-Textbooks, is a wiki for the creation of books. ... Self-Monitoring, Analysis, and Reporting Technology, or S.M.A.R.T., is a monitoring system for computer hard disks to detect and report on various indicators of reliability, in the hope of anticipating failures. ...


However, not all failures are predictable. Normal use eventually can lead to a breakdown in the inherently fragile device, which makes it essential for the user to periodically back up the data onto a separate storage device. Failure to do so can lead to the loss of data. While it may be possible to recover lost information, it is normally an extremely costly procedure, and it is not possible to guarantee success. A 2007 study published by Google suggested very little correlation between failure rates and either high temperature or activity level.[32] While several S.M.A.R.T. parameters have an impact on failure probability, a large fraction of failed drives do not produce predictive S.M.A.R.T. parameters.[32] S.M.A.R.T. parameters alone may not be useful for predicting individual drive failures.[32] This article is about the corporation. ...


SCSI, SAS and FC drives are typically more expensive and are traditionally used in servers and disk arrays, whereas inexpensive ATA and SATA drives evolved in the home computer market and were perceived to be less reliable. This distinction is now becoming blurred. Look up server in Wiktionary, the free dictionary. ... Hewlett-Packard Disk-Arrays: HASS (top) and NIKE (OEMd Data General SCSI Clariion) EMC CLARiiON CX500 (Cover removed on one Shelf) EMC Symmetrix DMX1000 A disk array is an enterprise storage system which contains multiple disk drives. ... Children playing on a Amstrad CPC 464 in the 1980s. ...


The mean time between failures (MTBF) of SATA drives is usually about 600,000 hours (some drives such as Western Digital Raptor have rated 1.2 million hours MTBF), while SCSI drives are rated for upwards of 1.5 million hours.[citation needed] However, independent research indicates that MTBF is not a reliable estimate of a drive's longevity.[33] MTBF is conducted in laboratory environments in test chambers and is an important metric to determine the quality of a disk drive before it enters high volume production. Once the drive product is in production, the more valid[citation needed] metric is annualized failure rate (AFR). AFR is the percentage of real-world drive failures after shipping. Mean time between failures (MTBF) is the mean (average) time between failures of a system, the reciprocal of the failure rate in the special case when the failure rate is constant. ... The WD740GD The Western Digital Raptor (often marketed as WD Raptor) is a high-end hard disk drive series produced by Western Digital that created its own niche in the enthusiast and small-server market. ... Annualized failure rate, or short AFR is the reciprocal of the MTBF expressed in years and percent. ...


SAS drives are comparable to SCSI drives, with high MTBF and high[citation needed] reliability.


Enterprise SATA drives designed and produced for enterprise markets, unlike standard SATA drives, have reliability comparable to other enterprise class drives.[citation needed]


Typically enterprise drives (all enterprise drives, including SCSI, SAS, enterprise SATA and FC) experience between 0.70%-0.78% annual failure rates from the total installed drives.[citation needed]


Manufacturers

A Western Digital 3.5 inch 250 GB SATA HDD.
See also List of defunct hard disk manufacturers

The technological resources and know-how required for modern drive development and production mean that as of 2007, over 98% of the world's HDDs are manufactured by just a handful of large firms: Seagate (which now owns Maxtor), Western Digital, Samsung, and Hitachi (which owns the former disk manufacturing division of IBM). Fujitsu continues to make mobile- and server-class disks but exited the desktop-class market in 2001. Toshiba is a major manufacturer of 2.5-inch and 1.8-inch notebook disks. ExcelStor is a small HDD manufacturer. Image File history File links Metadata Size of this preview: 800 × 536 pixelsFull resolution‎ (3,872 × 2,592 pixels, file size: 1. ... Image File history File links Metadata Size of this preview: 800 × 536 pixelsFull resolution‎ (3,872 × 2,592 pixels, file size: 1. ... Western Digital Corporation (NYSE: WDC) (often abbreviated to WD) is a manufacturer of a large proportion of the worlds hard disks, and has a long history in the electronics industry as an IC maker and a storage products company. ... SATA redirects here. ... It has been estimated that over 200 companies were hard disk drive manufacturers at one time or another. ... Seagate Technology (NYSE: STX) is a major American manufacturer of hard drives, founded in 1979 and based in Scotts Valley, California. ... Maxtor Corporation was an American manufacturer of computer hard disk drives founded in 1982 and acquired by Seagate in 2006. ... Western Digital Corporation (NYSE: WDC) (often abbreviated to WD) is a manufacturer of a large proportion of the worlds hard disks, and has a long history in the electronics industry as an IC maker and a storage products company. ... Samsung Electronics (SEC, Hangul:삼성전자; KRXS: 005930, KRXS: 005935, LSE: SMSN, LSE: SMSD) is the worlds largest electronics and information technology company[1], headquartered in Suwon, South Korea. ... Hitachi Ltd. ... International Business Machines Corporation (IBM, or colloquially, Big Blue) (NYSE: IBM) (incorporated June 15, 1911, in operation since 1888) is headquartered in Armonk, New York, USA. The company manufactures and sells computer hardware, software, and services. ... For the district in Saga, Japan, see Fujitsu, Saga. ... Toshiba Corporations headquarters (Center) in Hamamatsucho, Tokyo Toshiba Corporation sales by division for year ending March 31, 2005 Toshiba Corporation ) (TYO: 6502 ) is a Japanese multinational conglomerate manufacturing company, headquartered in Tokyo, Japan. ... ExecelStor ES3220 20GB Drive ExcelStor is a small hard disk drive manufacturer established in 2000. ...


Dozens of former HDD manufacturers have gone out of business, merged, or closed their HDD divisions; as capacities and demand for products increased, profits became hard to find, and the market underwent significant consolidation in the late 1980s and late 1990s. The first notable casualty of the business in the PC era was Computer Memories Inc. or CMI; after an incident with faulty 20 MB AT disks in 1985,[34] CMI's reputation never recovered, and they exited the HDD business in 1987. Another notable failure was MiniScribe, who went bankrupt in 1990 after it was found that they had engaged in accounting fraud and inflated sales numbers for several years. Many other smaller companies (like Kalok, Microscience, LaPine, Areal, Priam and PrairieTek) also did not survive the shakeout, and had disappeared by 1993; Micropolis was able to hold on until 1997, and JTS, a relative latecomer to the scene, lasted only a few years and was gone by 1999, after attempting to manufacture HDDs in India. Their claim to fame was creating a new 3" form factor drive for use in laptops. Quantum and Integral also invested in the 3" form factor; but eventually gave up as this form factor failed to catch on.[citation needed] Rodime was also an important manufacturer during the 1980s, but stopped making disks in the early 1990s amid the shakeout and now concentrates on technology licensing; they hold a number of patents related to 3.5-inch form factor HDDs. Consolidation is the act of merging many things into one. ... Computer Memories Inc. ... MiniScribe was a manufacturer of disk storage products, founded in Longmont, Colorado in 1980. ... Kalok was a hard disk drive manufacturer which went bankrupt in 1994. ... Micropolis Corporation was a SCSI hard drive manufacturing company located in Chatsworth, California. ... JT Storage (also known as JTS) was a maker of inexpensive IDE hard drives for personal computers based in San Jose, California. ...

  • 1988: Tandon Corporation sold its disk manufacturing division to Western Digital (WDC), which was then a well-known controller designer.[35]
  • 1989: Seagate Technology bought Control Data's high-end disk business, as part of CDC's exit from hardware manufacturing.
  • 1990: Maxtor buys MiniScribe out of bankruptcy, making it the core of its low-end disk division.
  • 1994: Quantum bought DEC's storage division, giving it a high-end disk range to go with its more consumer-oriented ProDrive range, as well as the DLT tape drive range.
  • 1995: Conner Peripherals, which was founded by one of Seagate Technology's co-founders along with personnel from MiniScribe, announces a merger with Seagate, which was completed in early 1996.
  • 1996: JTS merges with Atari, allowing JTS to bring its disk range into production. Atari was sold to Hasbro in 1998, while JTS itself went bankrupt in 1999.
  • 2000: Quantum sells its disk division to Maxtor to concentrate on tape drives and backup equipment.
  • 2003: Following the controversy over mass failures of its Deskstar 75GXP range, HDD pioneer IBM sold the majority of its disk division to Hitachi, who renamed it Hitachi Global Storage Technologies (HGST).
  • December 21, 2005: Seagate and Maxtor announced an agreement under which Seagate would acquire Maxtor in an all stock transaction valued at $1.9 billion. The acquisition was approved by the appropriate regulatory bodies, and closed on May 19, 2006.
  • 2007
    • April: Hitachi releases the 1 TB Hitachi Deskstar 7K1000 (1TB = 1 trillion bytes, roughly 931.5 GiB).[36][37][38]
    • July: Western Digital (WDC) acquires Komag U.S.A, a thin-film media manufacturer, for USD 1 Billion.[39]
    • September: Hitachi releases 2.5-inch 320 GB hard disk.
  • 2008
    • January: Hitachi releases 2.5-inch 500 GB hard disk and it was demonstrated by Asus with a laptop at 1 TB storage in CES event, Las Vegas

Seagate Technology (NYSE: STX) is a major American manufacturer of hard drives, founded in 1979 and based in Scotts Valley, California. ... Control Data Corporation (CDC), was one of the pioneering supercomputer firms. ... MiniScribe was a manufacturer of disk storage products, founded in Longmont, Colorado in 1980. ... Quantum Corporation is a manufacturer of tape drive products, based in San Jose, California. ... Digital Equipment Corporation was a pioneering American company in the computer industry. ... A Super DLT I tape cartridge Digital Linear Tape (DLT) (previously called CompacTape) is a magnetic tape data storage technology developed by Digital Equipment Corporation from 1984 onwards. ... Conner Peripherals was a company that manufactured hard drives for personal computers. ... This article is about the corporate game company. ... Hasbro (NYSE: HAS) is an American toy and game company. ... DDS tape drive. ... For other uses of Backup, see Backup (disambiguation). ... The Deskstar is a computer hard drive. ... is the 355th day of the year (356th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Seagate Technology (NYSE: STX) is a major American manufacturer of hard drives, founded in 1979 and based in Scotts Valley, California. ... Maxtor Corporation was an American manufacturer of computer hard disk drives founded in 1982 and acquired by Seagate in 2006. ... is the 139th day of the year (140th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... This article is about a measurement term for data storage capacity. ... The term gib may refer to: a castrated male cat or ferret an abbreviation for gibibyte (GiB) or gibibit (Gib) an abbreviation for Gibraltar an abbreviation for Gib Board, itself an abbreviation of Gibraltar Board, all Winston Wallboards[1] tradenames for drywall (plasterboard). ...

See also

A standard ZIP100 Disk. ... Sequoia view is a free program for visualising hard disk usage by squares. ... Formatting a hard drive using MS-DOS Disk formatting is the process of preparing a hard disk or other storage medium for use, including setting up an empty file system. ... This article refers to the computer hard disk. ... This article refers to both flash and DRAM-based solid state drives. ... Automatic Acoustic Management, or AAM, is a feature available in most modern hard drives, although usually disabled by default. ... This article refers to both flash and DRAM-based solid state drives. ...

Notes and References

  1. ^ Other terms used to describe hard disk drives include disk drive, disk file, DASD (Direct Access Storage Device), fixed disk, CKD disk and Winchester Disk Drive (after the IBM 3340).
  2. ^ How Hard Disks Work, howstuffworks.com
  3. ^ New Ideas, TIME Magazine, September 24, 1956
  4. ^ Finally! The Samsung SPH-V5400, world's first cellphone with a hard drive, engadget.com, 6 September 2004
  5. ^ IBM OEM MR Head | Technology | The era of giant magnetoresistive heads
  6. ^ Brian Hayes, Terabyte Territory, American Scientist, Vol 90 No 3 (May-June 2002) p. 212
  7. ^ Seagate Momentus 2½" HDDs per webpage Jan 2008
  8. ^ Seagate Baracuda 3½" HDDs per webpage Jan 2008
  9. ^ Western Digital Scorpio 2½" and Greenpower 3½" HDDs per quarterly conference, July 2007
  10. ^ PC Magazine comparison of 136 desktops shows 60 in this HDD capacity range with 50 larger and 26 smaller capacities[1]
  11. ^ HGST Deskstar 7K1000[2]
  12. ^ Seagate Cheetah 15K.5[3]
  13. ^ Walter, Chip. "Kryder's Law", Scientific American, Verlagsgruppe Georg von Holtzbrinck GmbH, 25 July 2005. Retrieved on 2006-10-29. 
  14. ^ Seagate Outlines the Future of Storage :: Articles :: www.hardwarezone.com®
  15. ^ 500GB SATA drives reviews
  16. ^ a b Hitachi's 7K1000 Terabyte Hard Drive
  17. ^ Seagate, Samsung Begin to Ship 1 TB Desktop Hard Drives
  18. ^ WD Caviar GP: The "Green" 1 TB Drive
  19. ^ Seagate Elite 47, shipped 12/97 per 1998 Disk/Trend Report - Rigid Disk Drives
  20. ^ Quantum Bigfoot TS, shipped 10/98 per 1999 Disk/Trend Report - Rigid Disk Drives
  21. ^ The Quantum Bigfoot TS used a maximum of 3 platters, other earlier and lower capacity product used up to 4 platters in a 5.25" HH form factor, e.g. Microscience HH1090 circa 1989.
  22. ^ Hitachi announces 500GB laptop drive. 080103 http://www.macworld.com
  23. ^ Samsung unveils 160GB iPod-sized drive. 070808 macnn.com
  24. ^ SDK Starts Shipments of 1.3-Inch PMR-Technology-Based HD Media
  25. ^ 1.3" HDD Product Specification, Samsung, 2008
  26. ^ Toshiba's 0.85-inch HDD is set to bring multi-gigabyte capacities to small, powerful digital products, Toshiba press release, 8 January 2004
  27. ^ Toshiba enters Guinness World Records Book with the world's smallest hard disk drive, Toshiba press release, 16 March 2004
  28. ^ Flash price fall shakes HDD market, EETimes Asia, 1 August 2007.
  29. ^ Untitled Document
  30. ^ Pugh et al; "IBM's 360 and Early 370 Systems;" MIT Press, 1991, pp.270
  31. ^ Toshiba HDD Protection measures.
  32. ^ a b c Barroso, L.A., et al. Failure Trends in a Large Disk Drive Population. February 2007.
  33. ^ Everything You Know About Disks Is Wrong. StorageMojo (February 20, 2007). Retrieved on 2007-08-29.
  34. ^ Apparently the CMI disks suffered from a higher soft error rate than IBM's other suppliers (Seagate and MiniScribe) but the bugs in Microsoft's DOS Operating system may have turned these recoverable errors into hard failures. At some point, possibly MS-DOS 3.0, soft errors were reported as disk hard errors and a subsequent Microsoft patch turned soft errors into corrupted memory with unpredictable <link rel="stylesheet" type="text/css" href="http://en.wikipedia.org/w/index.php?title=User:Lupin/navpop.css&action=raw&ctype=text/css&dontcountme=s">results ("crashes"). MS-DOS 3.3 apparently resolved this series of problems but by that time it was too late for CMI. See also, "IBM and CMI in Joint Effort to Rehab AT Hard-Disk Rejects," PC Week, v.2 n.11, p.1, March 19, 1985
  35. ^ COMPANY NEWS; Tandon Sells Disk Drive Unit. The New York Times (1988-03-09). Retrieved on 2008-02-22.
  36. ^ Hitachi ships first 1TB hard drive. Retrieved on 2007-12-12.
  37. ^ First hands-on with the only 1 TB drive. Retrieved on 2007-08-13.
  38. ^ Hitachi Deskstar 7K1000 Terabyte Hard Drive Review. Retrieved on 2007-08-13.
  39. ^ Western Digital buys Komag for $1 Billion. Retrieved on 2007-08-18.

Magnetic disk storage is a critical component of the computer revolution. ... (Clockwise from upper left) Time magazine covers from May 7, 1945; July 25, 1969; December 31, 1999; September 14, 2001; and April 21, 2003. ... American Scientist (ISSN 0003-0996) is an illustrated bimonthly magazine about science and technology. ... is the 206th day of the year (207th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 302nd day of the year (303rd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 241st day of the year (242nd in leap years) in the Gregorian calendar. ... Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ... The New York Times is a daily newspaper published in New York City and distributed internationally. ... Year 1988 (MCMLXXXVIII) was a leap year starting on Friday (link displays 1988 Gregorian calendar). ... is the 68th day of the year (69th in leap years) in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... is the 53rd day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 346th day of the year (347th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 225th day of the year (226th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 225th day of the year (226th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 230th day of the year (231st in leap years) in the Gregorian calendar. ...

External links

Wikimedia Commons has media related to:
Hard disk
  • Magnetic image of 120MB hard drive / Image And Sound Forensics(TM)
  • http://www.youtube.com/watch?v=9eMWG3fwiEU Video of opened hard drive performing several operations.
  • Factfile: Hard disk drive - How they work from the BBC
  • The Hard Disk That Changed The World [re: RAMAC], Newsweek, August 7, 2006
  • TechEncyclopedia about Hard Disks
  • Hard disk interfaces pinouts
  • War of the Disks: Hard Disk Drives vs. Flash Solid State Disks Despatches from the magneto / flash wars
  • PC Doctor takes you inside a hard drive
  • Failure Trends in a Large Disk Drive Population : Disk Failures report by Google Labs
  • Hard Disk Myths TecHarp / Photo Myth Snopes Urban Legend Archive
  • Disk Introduction: Detailed Introduction of the Disks with Graphic Details.
  • Describing a c.1975 HDD


  Results from FactBites:
 
Hard Disk Drive Guide - History (615 words)
In 1986 the first 3 /12" hard disks with voice coil actuators were introduced by Conner in volume, but half (1.6") and full height 5 1/4" drives persisted for several years.
This drive holds one gigabyte on a disk which is the size of an American quarter.
The world's first gigabyte-capacity disk drive, the IBM 3380, introduced in 1980, was the size of a refrigerator, weighed 550 pounds (about 250 kg), and had a price tag of $40,000.
Hard disk - Wikipedia, the free encyclopedia (3837 words)
It is important to note that hard drive manufacturers often use the metric definition of the prefixes "giga" and "mega." However, nearly all operating system utilities report capacities using binary definitions for the prefixes.
For many years, hard disks were large, cumbersome devices, more suited to use in the protected environment of a data center or large office than in a harsh industrial environment (due to their delicacy), or small office or home (due to their size and power consumption).
Before the early 1980s, most hard disks had 8-inch or 14-inch platters, required an equipment rack or a large amount of floor space (especially the large removable-media drives, which were often referred to as "washing machines"), and in many cases needed special power hookups for the large motors they used.
  More results at FactBites »

 
 

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