CacheFS

CacheFS is the name used for several similar software technologies designed to speed up Network file system file access for networked computers. A network file system is any computer File system that supports sharing of files, printers and other resources as Persistent storage over These technologies all operate in similar ways: they store (cache) copies of files on a local Hard disk so that if a file is accessed again, it can be done locally at much higher speeds than networks typically allow. In Computer science, a cache (kæʃ like "cash") is a collection of data duplicating original A hard disk drive ( HDD) commonly referred to as a hard drive, hard disk, or fixed disk drive, is a Non-volatile storage device

CacheFS software is used on several Unix-like operating systems. A Unix-like (sometimes shortened to *nix) Operating system is one that behaves in a manner similar to a Unix system while not necessarily conforming The original version was developed by Sun Microsystems in 1993. Sun Microsystems Inc ( is a multinational vendor of Computers computer components Computer software, and Information technology services Another version was written for Linux and released in 2003.

Network filesystems are dependent on a network link and a remote server; obtaining a file from such a filesystem can be significantly slower than getting the file locally. A computer network is a group of interconnected Computers. Networks may be classified according to a wide variety of characteristics A server is a Computer dedicated to providing one or more services over a computer network typically through a request-response routine In Computing, a file system (often also written as filesystem) is a method for storing and organizing Computer files and the data they contain to make For this reason, it can be desirable to cache data from these filesystems on a local disk, thus potentially speeding up future accesses to that data by avoiding the need to go to the network and fetch it again. The software has to check that the remote file has not changed since it was cached, but this is much faster than reading the whole file again.

1 Sun version
2 Linux version
3 Project status
4 Features
5 References
6 See also

Sun version

The first CacheFS implementation was developed by Sun Microsystems and released in the Solaris 2.3 operating system release in 1993, as part of an expanded feature set for the NFS or Network File System suite known as Open Network Computing Plus (ONC+). Sun Microsystems Inc ( is a multinational vendor of Computers computer components Computer software, and Information technology services Solaris is a Unix -based Operating system introduced by Sun Microsystems in 1992 as the successor to SunOS. Network File System (NFS is a Network file system protocol originally developed by Sun Microsystems in 1983 allowing a user on a client Computer to access ONC RPC, short for Open Network Computing Remote Procedure Call, is a widely deployed Remote procedure call system ^[1] It was subsequently used in other UNIX operating systems such as Irix (starting with the 5. IRIX is a computer Operating system developed by Silicon Graphics Inc 3 release in 1994). ^[2] ^[3]

Linux version

Linux operating systems now commonly use a new version of CacheFS developed by David Howells. Linux (commonly pronounced ˈlɪnəks Howells appears to have rewritten CacheFS from scratch, not using Sun's original code.

The Linux CacheFS currently is designed to operate on Andrew File System and Network File System filesystems. The Andrew File System ( AFS) is a distributed networked file system which uses a set of trusted servers to present a homogeneous location-transparent file name space Network File System (NFS is a Network file system protocol originally developed by Sun Microsystems in 1983 allowing a user on a client Computer to access

Terminology

Because of its similar naming to FS-Cache, CacheFS' terminology is confusing to outsiders. Terminology is the study of terms and their use Terms are Words and Compound words that are used in specific contexts CacheFS is a backend for FS-Cache and handles the actual data storage and retrieval. FS-Cache passes the requests from netfs to CacheFS.

FS-Cache

The cache facility/layer between the cache backends, like CacheFS, and NFS or AFS.

Cache Backends

CacheFS is a Filesystem for the FS-Cache facility. A block device can be used as cache by simply mounting it. Mounting, in Computer science, is the process of making a File system ready for use by the Operating system, typically by reading certain index data structures Needs no special activation and is deactivated by unmounting it.

Cachefiles(daemon)

Daemon using an existing filesystem (Ext3 with user_xattr) as cache. In Unix and other computer multitasking Operating systems a daemon (ˈdiːmən or /ˈdeɪmən/ is a Computer program that runs in the background The ext3 or third extended filesystem is a journaled file system that is commonly used by the Linux Operating system. Cache is bound with "cachefilesd -s".

Project status

Project status unknown.

Features

The facility can be conceptualised by the following diagram:

Image:cachefs diagram.jpg

The facility (known as FS-Cache) is designed to be as transparent as possible to a user of the system. A diagram is a 2D geometric symbolic Representation of Information according to some Visualization technique Applications should just be able to use NFS files as normal, without any knowledge of there being a cache.

References

^ New Features in Solaris 2.4 in the Solaris 2. 4 AnswerBook documentation, Sun Microsystems, 1994. Accessed Sept 10, 2007
^ IRIX 6.5 ONC3/NFS Administrators Guide, Silicon Graphics, 2005. Accessed Sept 10, 2007
^ History of IRIX, Ryan Thoryk, revision of January 18, 2007. Accessed Sept 10, 2007

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