| Developer(s) | Oracle Corporation |
|---|---|
| Full name | Oracle Cluster file System |
| Introduced | March 2006 with Linux 2.6.16 |
| Limits | |
| Max. volume size | 4 PB (OCFS2) [1] |
| Max. file size | 4 PB (OCFS2) [1] |
| Max. filename length | 255 bytes |
| Allowed characters in filenames | All bytes except NUL and '/' |
| Features | |
| Dates recorded | modification (mtime), attribute modification (ctime), access (atime) |
| File system permissions | Unix permissions, ACLs and arbitrary security attributes (Linux 2.6 and later) |
| Transparent compression | No |
| Transparent encryption | No |
| Data deduplication | No |
| Copy-on-write | Yes |
| Other | |
| Supported operating systems | Linux |
The Oracle Cluster File System (OCFS, in its second version OCFS2) is a shared disk file system developed by Oracle Corporation and released under the GNU General Public License. The first version of OCFS was developed with the main focus to accommodate Oracle's database management system that used cluster computing. Because of that it was not a POSIX-compliant file system. With version 2 the POSIX features were included.
OCFS2 (version 2) was integrated into the version 2.6.16 of Linux kernel. Initially, it was marked as "experimental" (Alpha-test) code. This restriction was removed in Linux version 2.6.19. With kernel version 2.6.29 in late 2008, more features were included into ocfs2, such as access control lists and quotas. [2] [3]
OCFS2 used a distributed lock manager which resembles the OpenVMS DLM but is much simpler. [4] Oracle announced version 1.6 in November 2010 which included a copy on write feature called reflink. [5]
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, some of which use it as the default file system.
The 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.
Reiser4 is a computer file system, successor to the ReiserFS file system, developed from scratch by Namesys and sponsored by DARPA as well as Linspire. Reiser4 was named after its former lead developer Hans Reiser. As of 2019, the Reiser4 patch set is still being maintained, but according to Phoronix, it is unlikely to be merged into mainline Linux without corporate backing.
In computing, the Global File System 2 or GFS2 is a shared-disk file system for Linux computer clusters. GFS2 allows all members of a cluster to have direct concurrent access to the same shared block storage, in contrast to distributed file systems which distribute data throughout the cluster. GFS2 can also be used as a local file system on a single computer.
Filesystem in Userspace (FUSE) is a software interface for Unix and Unix-like computer operating systems that lets non-privileged users create their own file systems without editing kernel code. This is achieved by running file system code in user space while the FUSE module provides only a "bridge" to the actual kernel interfaces.
Lustre is a type of parallel distributed file system, generally used for large-scale cluster computing. The name Lustre is a portmanteau word derived from Linux and cluster. Lustre file system software is available under the GNU General Public License and provides high performance file systems for computer clusters ranging in size from small workgroup clusters to large-scale, multi-site systems. Since June 2005, Lustre has consistently been used by at least half of the top ten, and more than 60 of the top 100 fastest supercomputers in the world, including the world's No. 1 ranked TOP500 supercomputer in June 2020, Fugaku, as well as previous top supercomputers such as Titan and Sequoia.
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.
Squashfs is a compressed read-only file system for Linux. Squashfs compresses files, inodes and directories, and supports block sizes from 4 KiB up to 1 MiB for greater compression. Several compression algorithms are supported. Squashfs is also the name of free software, licensed under the GPL, for accessing Squashfs filesystems.
The following tables compare general and technical information for a number of file systems.
The ext4 journaling file system or fourth extended filesystem is a journaling file system for Linux, developed as the successor to ext3.
LogFS is a Linux log-structured and scalable flash file system, intended for use on large devices of flash memory. It is written by Jörn Engel and in part sponsored by the CE Linux Forum.
JBD, or journaling block device, is a generic block device journaling layer in the Linux kernel written by Stephen Tweedie from Red Hat. JBD is filesystem-independent. ext3, ext4 and OCFS2 are known to use JBD.
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 initially designed at Oracle Corporation 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. According to Oracle, Btrfs "is not a true acronym".
Ceph is an open-source software storage platform, implements object storage on a single distributed computer cluster, and provides 3-in-1 interfaces for object-, block- and file-level storage. Ceph aims primarily for completely distributed operation without a single point of failure, scalable to the exabyte level, and freely available.
aufs implements a union mount for Linux file systems. The name originally stood for AnotherUnionFS until version 2.
The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was conceived and created in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU operating system, which was created as a free replacement for UNIX. Since then, it has spawned a plethora of operating system distributions, commonly also called Linux.
OrangeFS is an open-source parallel file system, the next generation of Parallel Virtual File System (PVFS). A parallel file system is a type of distributed file system that distributes file data across multiple servers and provides for concurrent access by multiple tasks of a parallel application. OrangeFS was designed for use in large-scale cluster computing and is used by companies, universities, national laboratories and similar sites worldwide.
bcachefs is a copy-on-write (COW) file system for Linux-based operating systems. Its primary developer Kent Overstreet first announced it in 2015, and efforts are ongoing to have it included in the mainline Linux kernel. It is intended to compete with the modern features of ZFS or btrfs, and the speed and performance of ext4 or XFS.
