Reiser4
Encyclopedia
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
. Named after its former lead developer Hans Reiser
, Reiser4's continued development is uncertain following his conviction for murder.
Some of the more advanced Reiser4 features (such as user-defined transactions) are also not available because of a lack of a VFS
API for them.
At present Reiser4 lacks a few standard file system features, such as an online repacker (similar to the defragmentation
utilities provided with other file systems). The creators of Reiser4 say they will implement these later, or sooner if someone pays them to do so.
balancing approach, in which underpopulated nodes will not be merged until a flush to disk except under memory pressure or when a transaction completes. Such a system also allows Reiser4 to create files and directories without having to waste time and space through fixed blocks.
, synthetic benchmarks performed by Namesys show that Reiser4 is 10 to 15 times faster than its most serious competitor ext3
working on files smaller than 1 KiB. Namesys's benchmarks suggest it is typically twice the performance of ext3 for general-purpose filesystem usage patterns.
and consequently is still not supported on many Linux distribution
s; however, its predecessor ReiserFS v3 has been widely adopted. Reiser4 is also available from Andrew Morton
's -mm kernel sources, and from Zen patch set. Linux kernel developers claim that Reiser4 does not follow Linux coding standards, but Hans Reiser
suggested political reasons.
on April 28, 2008, leaving the future of Reiser4 uncertain. After his arrest, employees of Namesys assured they would continue to work and that the events would not slow down the software development in the immediate future. In order to afford increasing legal fees, Hans Reiser announced on December 21, 2006 that he was going to sell Namesys; as of March 26, 2008, it had not been sold, although the website was unavailable. In January 2008, Edward Shishkin, an employee of and programmer for Namesys, was quoted in a CNET interview saying that "Commercial activity of Namesys has stopped." Shishkin and others continued the development of Reiser4, making source code available from Shishkin's web site, later relocated to kernel.org
. Since 2008, Namesys employees have received 100% of their sponsored funding from DARPA which is why Edward said 'commercial funding has stopped'.
In a mailing list post from July 2009, Edward Shishkin wrote that in the coming autumn, they would start exploring the opportunity of getting Reiser4 into the main Linux kernel. In a November 2009 interview with Phoronix
he said he was going to publish a plug-in design document for independent expert review. He aimed for January 2011, but as of June 2011, and with the 3.0 Branch of kernel in full development, Reiser4 has not yet been integrated into the mainline kernel.
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
file system
File system
A file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...
, successor to the ReiserFS
ReiserFS
ReiserFS is a general-purpose, journaled computer file system designed and implemented by a team at Namesys led by Hans Reiser. ReiserFS is currently supported on Linux . Introduced in version 2.4.1 of the Linux kernel, it was the first journaling file system to be included in the standard kernel...
file system, developed from scratch by Namesys
Namesys
Namesys was a California corporation responsible for the design and implementation of the ReiserFS and Reiser4 filesystems. It has been inactive since late 2007, and as of 2010, is listed with the State of California with a status of "Suspended". Owned by Hans Reiser, Namesys was based in Oakland,...
and sponsored by DARPA
Defense Advanced Research Projects Agency
The Defense Advanced Research Projects Agency is an agency of the United States Department of Defense responsible for the development of new technology for use by the military...
as well as Linspire
Linspire
Linspire, previously known as LindowsOS, was a commercial operating system based on Debian GNU/Linux and later Ubuntu. Linspire was published by Linspire, Inc. and focused on ease-of-use, targeting home PC users...
. Named after its former lead developer Hans Reiser
Hans Reiser
Hans Thomas Reiser is an American computer programmer, entrepreneur, and convicted murderer. He is the creator and primary developer of the ReiserFS computer file system, which is contained within the Linux kernel, as well as its attempted successor, Reiser4. In 2004 he founded Namesys, a...
, Reiser4's continued development is uncertain following his conviction for murder.
Features
Some of the goals of the Reiser4 file system are:- More efficient journalingJournaling file systemA journaling file system is a file system that keeps track of the changes that will be made in a journal before committing them to the main file system...
through wandering logs - More efficient support of small files, in terms of disk space and speed through block suballocationBlock suballocationBlock suballocation is a feature of some computer file systems which allows large blocks or allocation units to be used while making efficient use of "slack" space at the end of large files, space which would otherwise be lost for other use to internal fragmentation.In file systems that don't...
- Faster handling of directoriesDirectory (file systems)In computing, a folder, directory, catalog, or drawer, is a virtual container originally derived from an earlier Object-oriented programming concept by the same name within a digital file system, in which groups of computer files and other folders can be kept and organized.A typical file system may...
with large numbers of files - Flexible plugin infrastructure (through which special metadata types, encryptionEncryptionIn cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...
and compressionData compressionIn computer science and information theory, data compression, source coding or bit-rate reduction is the process of encoding information using fewer bits than the original representation would use....
will be supported) - Dynamically optimized disk-layout through allocate-on-flushAllocate-on-flushAllocate-on-flush is a computer file system feature implemented in the HFS+, XFS, Reiser4, ZFS, Btrfs and ext4 file systems...
(also called delayed allocation in XFSXFSXFS is a high-performance journaling file system created by Silicon Graphics, Inc. It is the default file system in IRIX releases 5.3 and onwards and later ported to the Linux kernel. XFS is particularly proficient at parallel IO due to its allocation group based design...
) - TransactionDatabase transactionA transaction comprises a unit of work performed within a database management system against a database, and treated in a coherent and reliable way independent of other transactions...
support
Some of the more advanced Reiser4 features (such as user-defined transactions) are also not available because of a lack of a VFS
Virtual file system
A virtual file system or virtual filesystem switch is an abstraction layer on top of a more concrete file system. The purpose of a VFS is to allow client applications to access different types of concrete file systems in a uniform way...
API for them.
At present Reiser4 lacks a few standard file system features, such as an online repacker (similar to the defragmentation
Defragmentation
In the maintenance of file systems, defragmentation is a process that reduces the amount of fragmentation. It does this by physically organizing the contents of the mass storage device used to store files into the smallest number of contiguous regions . It also attempts to create larger regions of...
utilities provided with other file systems). The creators of Reiser4 say they will implement these later, or sooner if someone pays them to do so.
Performance
Reiser4 uses B*-trees in conjunction with the dancing treeDancing tree
For the film Dancing tree, see Dancing tree In computer science, a dancing tree is a tree data structure, which is similar to B+ tree. Invented by Hans Reiser, for use by the Reiser4 file system...
balancing approach, in which underpopulated nodes will not be merged until a flush to disk except under memory pressure or when a transaction completes. Such a system also allows Reiser4 to create files and directories without having to waste time and space through fixed blocks.
, synthetic benchmarks performed by Namesys show that Reiser4 is 10 to 15 times faster than its most serious competitor ext3
Ext3
The ext3 or third extended filesystem is a journaled file system that is commonly used by the Linux kernel. It is the default file system for many popular Linux distributions, including Debian...
working on files smaller than 1 KiB. Namesys's benchmarks suggest it is typically twice the performance of ext3 for general-purpose filesystem usage patterns.
Integration with Linux
, Reiser4 has not yet been merged into the mainline Linux kernelLinux kernel
The Linux kernel is an operating system kernel used by the Linux family of Unix-like operating systems. It is one of the most prominent examples of free and open source software....
and consequently is still not supported on many Linux distribution
Linux distribution
A Linux distribution is a member of the family of Unix-like operating systems built on top of the Linux kernel. Such distributions are operating systems including a large collection of software applications such as word processors, spreadsheets, media players, and database applications...
s; however, its predecessor ReiserFS v3 has been widely adopted. Reiser4 is also available from Andrew Morton
Andrew Morton (computer programmer)
Andrew Keith Paul Morton is an Australian software engineer, best known as one of the lead developers of the Linux kernel...
's -mm kernel sources, and from Zen patch set. Linux kernel developers claim that Reiser4 does not follow Linux coding standards, but Hans Reiser
Hans Reiser
Hans Thomas Reiser is an American computer programmer, entrepreneur, and convicted murderer. He is the creator and primary developer of the ReiserFS computer file system, which is contained within the Linux kernel, as well as its attempted successor, Reiser4. In 2004 he founded Namesys, a...
suggested political reasons.
History of Reiser4
Hans Reiser was convicted of murderMurder
Murder is the unlawful killing, with malice aforethought, of another human being, and generally this state of mind distinguishes murder from other forms of unlawful homicide...
on April 28, 2008, leaving the future of Reiser4 uncertain. After his arrest, employees of Namesys assured they would continue to work and that the events would not slow down the software development in the immediate future. In order to afford increasing legal fees, Hans Reiser announced on December 21, 2006 that he was going to sell Namesys; as of March 26, 2008, it had not been sold, although the website was unavailable. In January 2008, Edward Shishkin, an employee of and programmer for Namesys, was quoted in a CNET interview saying that "Commercial activity of Namesys has stopped." Shishkin and others continued the development of Reiser4, making source code available from Shishkin's web site, later relocated to kernel.org
Kernel.org
Kernel.org is a main repository of source code for the Linux kernel, the base of the popular Linux operating system. It makes all versions of the source code available to all users. It also hosts various other projects, like Google Android...
. Since 2008, Namesys employees have received 100% of their sponsored funding from DARPA which is why Edward said 'commercial funding has stopped'.
Future of Reiser4
Reiser4 development still continues, delivering patches via kernel.org.In a mailing list post from July 2009, Edward Shishkin wrote that in the coming autumn, they would start exploring the opportunity of getting Reiser4 into the main Linux kernel. In a November 2009 interview with Phoronix
Phoronix
Phoronix is a technology website that offers product reviews, Linux distribution screenshots, interviews, and news while maintaining a pure Linux orientation. Phoronix was started in June 2004 by Michael Larabel, who currently serves as the owner and editor-in-chief. The name Phoronix is a...
he said he was going to publish a plug-in design document for independent expert review. He aimed for January 2011, but as of June 2011, and with the 3.0 Branch of kernel in full development, Reiser4 has not yet been integrated into the mainline kernel.
External links
- Current Reiserfs4 patches as Namesys'NamesysNamesys was a California corporation responsible for the design and implementation of the ReiserFS and Reiser4 filesystems. It has been inactive since late 2007, and as of 2010, is listed with the State of California with a status of "Suspended". Owned by Hans Reiser, Namesys was based in Oakland,...
website is down - Reiserfs v4 utilities and Reiserfs v3 utilities source code repository
- Compiling a new Kernel for Reiser4
- Installing your Linux Distribution on Reiser4
- Reiser4 homepage is now offline but try a cached version (without figures).
- Introduction to Reiser4 on kuro5hinKuro5hinKuro5hin is a collaborative discussion website. Articles are created and submitted by Kuro5hin's users and submitted to queue for evaluation. Site members can vote for or against publishing an article and, once the article has reached a certain number of votes, it is then published to the site...
- Reiser4 transaction design document
- Trees in the Reiser4 Filesystem, Part I from Linux JournalLinux JournalLinux Journal is a monthly technology magazine published by Belltown Media, Inc. of Houston, Texas. The magazine focuses specifically on Linux, allowing the content to be a highly specialized source of information for open source enthusiasts.-History:...
- Trees in the Reiser4 Filesystem, Part II from Linux JournalLinux JournalLinux Journal is a monthly technology magazine published by Belltown Media, Inc. of Houston, Texas. The magazine focuses specifically on Linux, allowing the content to be a highly specialized source of information for open source enthusiasts.-History:...
- Hans Reiser: The Reiser4 Filesystem Hans ReiserHans ReiserHans Thomas Reiser is an American computer programmer, entrepreneur, and convicted murderer. He is the creator and primary developer of the ReiserFS computer file system, which is contained within the Linux kernel, as well as its attempted successor, Reiser4. In 2004 he founded Namesys, a...
's lecture at GoogleGoogleGoogle Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program... - Why Reiser4 is not in the Linux Kernel at kernelnewbies.org and Hans Reiser's response to Kernelnewbies' criticism
- Reiser4 and the Politics of the Kernel by Bruce Byfield on Linux.com
- Reiser4 Wiki on kernel.orgKernel.orgKernel.org is a main repository of source code for the Linux kernel, the base of the popular Linux operating system. It makes all versions of the source code available to all users. It also hosts various other projects, like Google Android...
- The Reiser4 Filesystem: Ways In Which Extra Rigor In Scientific Methodology Can Consume Years Of Your Life, And How The Result Can Be So Very Worthwhile - lecture given by Hans Reiser at Stanford UniversityStanford UniversityThe Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...
(video archive). - Reiser4 Gentoo FAQ