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Encyclopedia > Installable File System

The Installable File System (IFS) is a Filesystem API in IBM OS/2 and Microsoft Windows NT that enables the operating system to recognize and load drivers for filesystems. A filesystem API is an application programming interface that allow developers to add support of a filesystem to an operating system without needing the second to know anything about what filesystem is it or how it works. ... OS/2 is an operating system created by Microsoft and IBM and later developed by IBM exclusively. ... Windows NT is a family of operating systems produced by Microsoft, and was succeeded by Windows 2000 (still based on Windows NT). ... In computing, an operating system ( aka, OS) is the system software responsible for the direct control and management of hardware and basic system operations. ... Device driver vehicle driver (driving) JDBC driver - a software that allows applications to connect to a database a kind of sail on a sailboat (driver (sail)) The golf club usually used for the first shot on a par 4 or 5 hole. ... See Filing system for this term as it is used in libraries and offices In computing, a file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. ...

Contents


History

When IBM and Microsoft were codeveloping OS/2 they did realize that FAT wasn't good enough for hard disks, and Microsoft begin developing the High Performance File System, codenamed Pinball. Fat is one of the three main classes of food and, at approximately 38 kJ (9 kilocalories) per gram, as compared to sugar with 17 kJ (4 kcal) per gram or ethanol with 29 kJ (7 kcal) per gram, the most concentrated form of metabolic energy available to humans. ... HPFS or High Performance File System, is a file system created specifically for the OS/2 operating system to improve upon the limitations of the FAT file system. ...


Instead of coding it inside the kernel, as FAT was, and as tradition used to be in contemporary operating systems, Microsoft developed a "driver-based" Filesystem API that could allow them and other developers add new filesystems to the kernel without needing to modify it. A filesystem API is an application programming interface that allow developers to add support of a filesystem to an operating system without needing the second to know anything about what filesystem is it or how it works. ...


When Microsoft stopped working on OS/2, IBM continued using the IFS interface and Microsoft implemented a similar one in their Windows NT product.


IFS in OS/2

The IFS provided a basic and powerful interface for programming filesystems. It was introduced in 1989 in OS/2 1.20, along with the HPFS filesystem.


Filesystem drivers executed in kernel-space (ring 0) and are divided in four principal pieces: microIFS, miniIFS, IFS, helpers. Ring 0 is the most privileged of four privilege levels in the x86 processor architecture, and is treated as kernel mode. ...


Only the IFS is required and is the filesystem code itself, and is loaded via a "IFS=" statement in the CONFIG.SYS file. It is a NE 16-bit dynamically loaded library. No matter if it is a 32-bit OS/2 (2.0 and upper), the IFS is always 16-bit (although extraofficially you can make a 32-bit IFS). The NE, or New Executable, is a new executable format that was introduced with OS/2 and Windows, and that was also used later in DOS 4. ... Illustration of an application which may use libvorbisfile. ...


The microIFS is a piece of code that loads in memory the kernel and the miniIFS and jumps to kernel execution. It is usually in the boot portion of the filesystem.


The miniIFS is a piece of code that is called by the kernel to load the first IFS statement that appers in the CONFIG.SYS file, so the first IFS statement must be the boot's filesystem for the system to be able to boot.


The helpers are 16-bit (for OS/2 1.x) or 32-bit (for OS/2 2.x and upper), are executed in user-space (ring 3) and contain the code used to typical filesystem maintenance, and are called by CHKDSK and FORMAT utilities. User mode refers to the mode that a kernel executes applications in. ... CHKDSK (command shortening of Checkdisk) is a command in DOS and Microsoft Windows systems which verifies a hard disk or a floppy disk for file system integrity. ... Formatting a hard drive using MS-DOS Disk formatting is the process of preparing a hard disk or other storage medium for use with the file system (FAT, NTFS, UFS, etc. ...


This four-piece scheme allowed developers to dynamically add a new bootable filesystem, as the ext2 driver for OS/2 demonstrated. The ext2 or second extended file system is a file system for the Linux kernel. ...


CD-ROM filesystem driver (ISO9660) was added in OS/2 2.0, UDF was added in OS/2 4.0 and JFS was added in OS/2 4.5. eComStation, the latest packaging of OS/2, also includes a lot of filesystem drivers for OS/2 in its companion CDs. There was also an official HPFS IFS made in 32-bit, called HPFS386 that improved performance and added some features, like variable size cache and Access Control Lists, and was available only in OS/2 3.0 server edition. The FAT filesystem was never removed from the kernel and officially never an IFS, although there are FAT IFS that added features like LFNs, FAT32 support, etc. The CD-ROM (an abbreviation for Compact Disc Read-Only Memory (ROM)) is a non-volatile optical data storage medium using the same physical format as audio compact discs, readable by a computer with a CD-ROM drive. ... ISO 9660, a standard published by the International Organization for Standardization, defines a file system for CD-ROM media. ... For other less-common meanings of UDF, see UDF (disambiguation). ... JFS is a journaling filesystem created by IBM. It is available under an open source license. ... HPFS or High Performance File System, is a file system created specifically for the OS/2 operating system to improve upon the limitations of the FAT file system. ... The access control list (ACL) is a concept in computer security, used to enforce privilege separation. ... Fat is one of the three main classes of food and, at approximately 38 kJ (9 kilocalories) per gram, as compared to sugar with 17 kJ (4 kcal) per gram or ethanol with 29 kJ (7 kcal) per gram, the most concentrated form of metabolic energy available to humans. ... Fat is one of the three main classes of food and, at approximately 38 kJ (9 kilocalories) per gram, as compared to sugar with 17 kJ (4 kcal) per gram or ethanol with 29 kJ (7 kcal) per gram, the most concentrated form of metabolic energy available to humans. ...


Network file-sharing protocols like NFS and SMB are also implemented using IFS, and the IFS interface never changed. Network File System (NFS) is a protocol originally developed by Sun Microsystems in 1984 and defined in RFCs 1094, 1813, and 3530 (obsoletes 3010), as a distributed file system which allows a computer to access files over a network as easily as if they were on its local disks. ... This article needs to be cleaned up to conform to a higher standard of quality. ...


IFS in Windows

When Microsoft stopped developing OS/2 and concentrated in Windows NT, they took the IFS ideas to it, along with the HPFS filesystem.


Instead of being a four-piece scheme they took a two-piece scheme. microIFS and miniIFS were removed from the scheme and IFS and helpers remain as the same, but adding a helper for defragging. The older NTLDR were coded for loading the NT kernel from FAT, HPFS or NTFS, but newer ones removed HPFS support. Fat is one of the three main classes of food and, at approximately 38 kJ (9 kilocalories) per gram, as compared to sugar with 17 kJ (4 kcal) per gram or ethanol with 29 kJ (7 kcal) per gram, the most concentrated form of metabolic energy available to humans. ... HPFS or High Performance File System, is a file system created specifically for the OS/2 operating system to improve upon the limitations of the FAT file system. ... NTFS or New Technology File System is the standard file system of Windows NT and its descendants Windows 2000, Windows XP and Windows Server 2003. ... HPFS or High Performance File System, is a file system created specifically for the OS/2 operating system to improve upon the limitations of the FAT file system. ...


The drivers became all 32-bit using PE executables, as well as the helpers.


FAT was in a IFS instead of in the kernel and get heavily optimized for performance and taking advantage of the 32-bit processing capabilities (being called FASTFAT).


Original Windows NT 3.1 incorpored FAT, HPFS (Pinball) and the newly created NTFS drivers, along with a new and improved CD-ROM filesystem driver that incorpored long file names using the Microsoft Joliet filesystem. Windows NT 3.5 added per-file compression to NTFS and to the IFS interface. In Windows NT 4.0 the HPFS was removed, in Windows 2000 FASTFAT was updated to support FAT32 and UDF was added. Windows 2000 also modified the IFS interface to add per-file encryption. Fat is one of the three main classes of food and, at approximately 38 kJ (9 kilocalories) per gram, as compared to sugar with 17 kJ (4 kcal) per gram or ethanol with 29 kJ (7 kcal) per gram, the most concentrated form of metabolic energy available to humans. ... HPFS or High Performance File System, is a file system created specifically for the OS/2 operating system to improve upon the limitations of the FAT file system. ... NTFS or New Technology File System is the standard file system of Windows NT and its descendants Windows 2000, Windows XP and Windows Server 2003. ... The CD-ROM (an abbreviation for Compact Disc Read-Only Memory (ROM)) is a non-volatile optical data storage medium using the same physical format as audio compact discs, readable by a computer with a CD-ROM drive. ... Joliet is the name of an extension to the ISO 9660 file system. ... NTFS or New Technology File System is the standard file system of Windows NT and its descendants Windows 2000, Windows XP and Windows Server 2003. ... HPFS or High Performance File System, is a file system created specifically for the OS/2 operating system to improve upon the limitations of the FAT file system. ... For other less-common meanings of UDF, see UDF (disambiguation). ...


Network file-sharing protocols and antivirus are also implemented using IFS.


The IFS interface changes in every Windows version, making it almost impossible to use an IFS designed for one Windows version to work in another.


Bibliography

  • O'Reilly - Windows NT File System Internals, A Developer's Guide - By Rajeev Nagar - ISBN 1-56592-249-2
  • Microsoft Press - Inside Windows NT File System - By Helen Custer - ISBN 1-55615-660-X
  • Microsoft Press - Inside Windows NT - By Helen Custer - ISBN 1-55615-481-X

See also

In computing, a file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. ... A filesystem API is an application programming interface that allow developers to add support of a filesystem to an operating system without needing the second to know anything about what filesystem is it or how it works. ... Virtual file system or Virtual filesystem switch (VFS) is a standard and abstract software layer that allows the operating system kernel (e. ... The following lists identify, characterise and link to fuller information on computer file systems. ... The following tables compare general and technical information for a number of file systems. ... A Virtual file system or Virtual filesystem switch (VFS) is an abstraction layer on top of a more concrete file system. ...

External links


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