InterMezzo was a

distributed file system A clustered file system (CFS) is a file system which is shared by being simultaneously Mount (computing), mounted on multiple Server (computing), servers. There are several approaches to computer cluster, clustering, most of which do not emplo ...

written for the

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 ...

, distributed under the

GNU General Public License 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 ...

. It was included in the standard Linux

kernel Kernel may refer to: Computing * Kernel (operating system), the central component of most operating systems * Kernel (image processing), a matrix used for image convolution * Compute kernel, in GPGPU programming * Kernel method, in machine learnin ...

from version 2.4.15 but was dropped from version 2.6. InterMezzo is designed to work on top of an existing

journaling file system A journaling file system is a file system that keeps track of changes not yet committed to the file system's main part by recording the goal of such changes in a data structure known as a " journal", which is usually a circular log. In the ev ...

such as

ext3 ext3, or third extended filesystem, is a journaling file system, journaled file system that is commonly used with the Linux kernel. It used to be the default file system for many popular Linux distributions but generally has been supplanted by ...

, JFS,

ReiserFS 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 syst ...

XFS 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; a ...

. It was developed around 1999. An InterMezzo system consists of a

server Server may refer to: Computing *Server (computing), a computer program or a device that provides requested information for other programs or devices, called clients. Role * Waiting staff, those who work at a restaurant or a bar attending custome ...

, which holds the master copy of the file system, and one or more clients with a

cache Cache, caching, or caché may refer to: Science and technology * Cache (computing), a technique used in computer storage for easier data access * Cache (biology) or hoarding, a food storing behavior of animals * Cache (archaeology), artifacts p ...

of the file system. It works either in a replication mode, in which a client maintains a duplicate of the entire file system, or in an on-demand mode in which the client only requests files that it needs. It does this by capturing all writes to the server's file system

journal A journal, from the Old French ''journal'' (meaning "daily"), may refer to: *Bullet journal, a method of personal organization *Diary, a record of personal secretive thoughts and as open book to personal therapy or used to feel connected to onesel ...

and streaming them to the client systems to be replayed. InterMezzo is described as a "high availability file system" since a client can continue to operate even if the connection to the server is lost. During a period of disconnection, updates are logged and will be propagated when the connection is restored. Conflicts are detected and handled according to a "conflict resolution policy" (although the best policy is likely to be to avoid conflicts). Typical applications of replication mode are: * A cluster of servers operating on a shared file system. * Computers that are not always connected to the network, such as

laptop A laptop computer or notebook computer, also known as a laptop or notebook, is a small, portable personal computer (PC). Laptops typically have a Clamshell design, clamshell form factor (design), form factor with a flat-panel computer scree ...

s. Typical applications of on-demand mode were distributed file serving, such as

File Transfer Protocol The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and d ...

(FTP) or

WWW The World Wide Web (WWW or simply the Web) is an information system that enables Content (media), content sharing over the Internet through user-friendly ways meant to appeal to users beyond Information technology, IT specialists and hobbyis ...

, or desktop workstations. InterMezzo was started as part of the Coda file system project at

Carnegie Mellon University Carnegie Mellon University (CMU) is a private research university in Pittsburgh, Pennsylvania, United States. The institution was established in 1900 by Andrew Carnegie as the Carnegie Technical Schools. In 1912, it became the Carnegie Institu ...

and took many design decisions from Coda (but did not share code). Coda in turn was a branch from the OpenAFS project. It was designed for enhanced scalability, performance, modularity, and easy integration with existing file systems. A paper was presented at an Open Source Convention in August 1999 by Peter J. Braam, Michael Callahan, and Phil Schwan. A company called Stelias Computing created a web site in late 1999, and announced a "beta" test version in January 2000. Although it was supported in the standard Linux kernel in version 2.4, InterMezzo was removed in the 2.6 series. Its developers moved on to a new project named Lustre at a company called Cluster File Systems, around 2001. Development continued through about 2003, and the web site was maintained through 2008.

References

External links

Debian Bug report logs on InterMezzo, mentioning Lustre
{{DEFAULTSORT:Intermezzo (File System) Network file systems Virtualization software for Linux Distributed file systems supported by the Linux kernel

See also

References

External links