| Developer(s) | Ge (Frank) Xia |
|---|---|
| Full name | Xia file system |
| Introduced | December 1993 |
| Discontinued | 14 January 1997 with Linux 2.1.21 |
| Limits | |
| Max volume size | 2 GB |
| Max file size | 64 MB |
| Other | |
| Supported operating systems | Linux |
Xiafs was a file system for the Linux kernel which was conceived and developed by Ge (Frank) Xia and was based on the MINIX file system. [1] Today it is obsolete and not in use, except possibly in some historic installations.
Linux originally used the MINIX file system, but it had a number of limitations. For example, the length of filenames was limited to 14 characters and the partition size was limited to 64 MB. To replace the MINIX file system, the extended file system (or ext) was developed. However, ext retained some problems such as poor performance and the lack of some date stamps. Two contenders for replacing ext were quickly developed: ext2 and Xiafs. The two file systems were included in the standard kernel in December 1993 (Linux 0.99.15). ext2 and Xiafs had the same goal: To offer good performance, reasonable limitations, and fixing the flaws of ext. Initially, Xiafs was more stable than ext2, but being a fairly minimalistic modification of the MINIX file system, it was not very well suited for future extension. [2] [3]
The result was that Xiafs changed very little while ext2 evolved considerably, rapidly improving stability and performance, and adding extensions. ext2, after some shakedown time, quickly became the standard file system of Linux. Since then, ext2 has developed into a very mature and robust file system.
Xiafs and the original ext were removed from Linux version 2.1.21, as they were no longer in use and were not maintained. ext2, ext3, and their successor ext4 are in the Linux kernel. As an exercise in computer history and as a file system tutorial, Xiafs was ported to modern Linux in 2013. [4]
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Xiafs was less powerful and offered less functionality than ext2. The maximum size of a file was 64 MiB and the maximum size of a partition was 2 GiB. While this was an improvement over ext, it did not measure up to ext2. Xiafs used less disk space for its control structures and it had greater stability at that time.
XFS is a high-performance 64-bit journaling file system created by Silicon Graphics, Inc (SGI) in 1993. It was the default file system in SGI's IRIX operating system starting with its version 5.3. XFS was ported to the Linux kernel in 2001; as of June 2014, XFS is supported by most Linux distributions; Red Hat Enterprise Linux uses it as its default file system.
ReiserFS is a general-purpose, journaling file system initially designed and implemented by a team at Namesys led by Hans Reiser and licensed under GPLv2. Introduced in version 2.4.1 of the Linux kernel, it was the first journaling file system to be included in the standard kernel. ReiserFS was the default file system in Novell's SUSE Linux Enterprise until Novell decided to move to ext3 for future releases on October 12, 2006.
ext2, or second extended file system, is a file system for the Linux kernel. It was initially designed by French software developer Rémy Card as a replacement for the extended file system (ext). Having been designed according to the same principles as the Berkeley Fast File System from BSD, it was the first commercial-grade filesystem for Linux.
ext3, or third extended filesystem, is a journaled file system that is commonly used by the Linux kernel. It used to be the default file system for many popular Linux distributions. Stephen Tweedie first revealed that he was working on extending ext2 in Journaling the Linux ext2fs Filesystem in a 1998 paper, and later in a February 1999 kernel mailing list posting. The filesystem was merged with the mainline Linux kernel in November 2001 from 2.4.15 onward. Its main advantage over ext2 is journaling, which improves reliability and eliminates the need to check the file system after an unclean shutdown. Its successor is ext4.
The Minix file system is the native file system of the Minix operating system. It was written from scratch by Andrew S. Tanenbaum in the 1980s and aimed to replicate the structure of the Unix File System while omitting complex features, and was intended to be a teaching aid. It largely fell out of favour among Linux users by 1994 due to the popularity of other filesystems - most notably ext2 - and its lack of features, including limited partition sizes and filename length limits.
The extended file system, or ext, was implemented in April 1992 as the first file system created specifically for the Linux kernel. Although EXT is not a specific file system name, it has been succeeded by EXT2, EXT3 and EXT 4. It has metadata structure inspired by traditional Unix filesystem principles, and was designed by Rémy Card to overcome certain limitations of the MINIX file system. It was the first implementation that used the virtual file system (VFS), for which support was added in the Linux kernel in version 0.96c, and it could handle file systems up to 2 gigabytes (GB) in size.
Stephen C. Tweedie is a Scottish software developer who is known for his work on the Linux kernel, in particular his work on filesystems.
Rémy Card is a French software developer who is credited as one of the primary developers of the Extended file system (ext) and Second Extended file system (ext2) for Linux.
Theodore Yue Tak Ts'o is an American software engineer mainly known for his contributions to the Linux kernel, in particular his contributions to file systems. He is the secondary developer and maintainer of e2fsprogs, the userspace utilities for the ext2, ext3, and ext4 filesystems, and is a maintainer for the ext4 file system.
Extended file attributes are file system features that enable users to associate computer files with metadata not interpreted by the filesystem, whereas regular attributes have a purpose strictly defined by the filesystem. Unlike forks, which can usually be as large as the maximum file size, extended attributes are usually limited in size to a value significantly smaller than the maximum file size. Typical uses include storing the author of a document, the character encoding of a plain-text document, or a checksum, cryptographic hash or digital certificate, and discretionary access control information.
The following tables compare general and technical information for a number of file systems.
e2fsprogs is a set of utilities for maintaining the ext2, ext3 and ext4 file systems. Since those file systems are often the default for Linux distributions, it is commonly considered to be essential software.
ext4 is a journaling file system for Linux, developed as the successor to ext3.
Cryptoloop is a Linux kernel's disk encryption module that relies on the Crypto API, which is a cryptography framework introduced in version 2.5.45 of the Linux kernel mainline. Cryptoloop was first introduced in the 2.5.x kernel series; its functionality was later incorporated into the device mapper, a generic framework used to map one block device onto another.
Fiwix is an operating system kernel based on the UNIX architecture and fully focused on being POSIX compatible. It is designed and developed mainly as a hobbyist operating system, but it also serves for educational purposes. It runs on the i386 hardware platform and is compatible with a good base of existing GNU applications. It follows the UNIX System V application binary interface and is also mostly Linux 2.0 system call ABI compatible.
Btrfs is a computer storage format that combines a file system based on the copy-on-write (COW) principle with a logical volume manager, developed together. It was created by Chris Mason in 2007 for use in Linux, and since November 2013, the file system's on-disk format has been declared stable in the Linux kernel.
In computer operating systems, mkfs is a command used to format a block storage device with a specific file system. The command is part of Unix and Unix-like operating systems. In Unix, a block storage device must be formatted with a file system before it can be mounted and accessed through the operating system's filesystem hierarchy.
The Orlov block allocator is an algorithm to define where a particular file will reside on a given file system (blockwise), so as to speed up disk operations.
An HTree is a specialized tree data structure for directory indexing, similar to a B-tree. They are constant depth of either one or two levels, have a high fanout factor, use a hash of the filename, and do not require balancing. The HTree algorithm is distinguished from standard B-tree methods by its treatment of hash collisions, which may overflow across multiple leaf and index blocks. HTree indexes are used in the ext3 and ext4 Linux filesystems, and were incorporated into the Linux kernel around 2.5.40. HTree indexing improved the scalability of Linux ext2 based filesystems from a practical limit of a few thousand files, into the range of tens of millions of files per directory.
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