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AdvFS, also known as Tru64 UNIX Advanced File System, is a file system developed in the late 1980s to mid-1990s by
Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until ...
for their OSF/1 version of the
Unix Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...
operating system (later Digital UNIX/Tru64 UNIX). In June 2008, it was released as free software under the GPL-2.0-only license.Press release concerning the release of the AdvFS source code
/ref> AdvFS has been used in high-availability systems where fast recovery from downtime is essential.


Functionality

AdvFS uses a relatively advanced concept of a storage pool (called a file domain) and of logical file systems (called file sets). A file domain is composed of any number of block devices, which could be partitions, LVM or LSM devices. A file set is a logical file system created in a single file domain. Administrators can add or remove volumes from an active file domain, providing that there is enough space on the remaining file domain, in case of removal. This was one of the trickier original features to implement because all data or metadata residing on the disk being removed had to first be migrated, online, to other disks, prior to removal. File sets can be balanced, meaning that file content of file sets be balanced across physical volumes. Particular files in a file set can be striped across available volumes. Administrators can take a snapshot (or clone) of any active or inactive file set. This allows for easy on-line backups and editing. Another feature allows administrators to add or remove block devices from a file domain, while the file domain has active users. This add/remove feature allows migration to larger devices or migration from potentially failing hardware without a system shutdown.


Features

Its features include: * a journal to allow for fast crash recovery *
undeletion Undeletion is a feature for restoring computer files which have been removed from a file system by file deletion. Deleted data can be recovered on many file systems, but not all file systems provide an undeletion feature. Recovering data with ...
support * high performance * dynamic structure that allows an administrator to manage the file system on the fly * on the fly creation of snapshots * defragmentation while the domain has active users Under Linux, AdvFS supports an additional ‘’syncv’’ system call to atomically commit changes to multiple files.


History

''AdvFS'', also known as ''Tru64 UNIX Advanced File System'', was developed by
Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until ...
engineer Engineers, as practitioners of engineering, are professionals who Invention, invent, design, build, maintain and test machines, complex systems, structures, gadgets and materials. They aim to fulfill functional objectives and requirements while ...
s beginning in the late 1980s in
Bellevue, WA Bellevue ( ) is a city in the Eastside region of King County, Washington, United States, located across Lake Washington from Seattle. It is the third-largest city in the Seattle metropolitan area, and the fifth-largest city in Washington. ...
(DECwest). It started out as the filesystem of the canceled OZIX operating system project. It was first delivered on the DEC OSF/1 system (later Digital UNIX/Tru64 UNIX). Over time, development moved to teams located in Bellevue, WA and Nashua, NH. Versions were always one version number behind the operating system version. Thus, DEC OSF/1 v3.2 had AdvFS v2.x, Digital UNIX 4.0 had AdvFS v3.x and Tru64 UNIX 5.x had AdvFS v4.x. It is generally considered that only AdvFS v4 had matured to production level stability, with a sufficient set of tools to get administrators out of any kind of trouble. The original team had enough confidence in its log based recovery to release it without an "fsck" style recovery utility on the assumption that the file system journal would always be allocated on mirrored drives. In 1996, Lee and Thekkath described the use of AdvFS on top of a novel disk virtualisation layer known as ''Petal''. In a later paper, Thekkath et al. describe their own file system (''Frangipani'') built on top of ''Petal'' and compare it to the performance of AdvFS running on the same storage layer. Shapiro and Miller compared the performance of files stored in AdvFS to Oracle RDBMS version 7.3.4 BLOB storage. Compaq Sierra Parallel File System (PFS) created a cluster file system based on multiple local AdvFS filesystems; testing carried out at
Lawrence Livermore National Laboratory Lawrence Livermore National Laboratory (LLNL) is a Federally funded research and development centers, federally funded research and development center in Livermore, California, United States. Originally established in 1952, the laboratory now i ...
(LLNL) in 2000–2001 found that while the underlying AdvFS filesystem had adequate performance (albeit with high CPU utilisation), the PFS clustering layer on top of it performed poorly.Uselton, A C. The Performance of PFS, the Compaq Sierra Product’s Parallel File System. United States: N. p., 2001. Web. doi:10.2172/15006183
Available online
/ref> On June 23, 2008, its
source code In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer. Since a computer, at base, only ...
was released by
Hewlett-Packard The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company. It was founded by Bill Hewlett and David Packard in 1939 in a one-car garage in Palo Alto, California ...
under the GPL-2.0-only license (instead of the recently released
GPLv3 The GNU General Public Licenses (GNU GPL or simply GPL) are a series of widely used free software licenses, or ''copyleft'' licenses, that guarantee end users the freedom to run, study, share, or modify the software. The GPL was the first ...
) at
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in order to be compatible with the also GPL-2.0-only licensed
Linux kernel The Linux kernel is a Free and open-source software, free and open source Unix-like kernel (operating system), kernel that is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the k ...
.


References


External links


Source code
at Sourceforge.net {{DEFAULTSORT:Advfs Digital Equipment Corporation Disk file systems Formerly proprietary software