Modern Distributed Filesystems For Linux: An Introduction
What Are Distributed Filesystems?
The ability to share disks, directories, and files over a network is one of the most significant advances in modern computing, reducing local disk space requirements and making it easy for users to collaborate without ending up with hundreds of versions of the same files. Personal computers running Microsoft Windows and Apple's MacOS and Mac OS X inherently support sharing disks and directories with other systems of the same types. Linux and Unix systems traditionally use the NFS network filesystem in order to do the same sort of thing.
NFS is the best-known network file-sharing mechanism for Unix, Linux, and related operating systems because it is included in most Unix-like operating system distributions and is trivial to configure. NFS is supported in the Linux kernel and NFS-related utilities are provided with every Linux distribution. However, a number of more modern mechanisms for sharing files and directories over networks are available for today's Linux systems. Each of these can provide significant administrative and usability advantages for sites running Linux.
Distributed filesystems such as OpenAFS (http://www.openafs.org) are Open Source releases of distributed filesystems that have been in commercial use for over a decade (AFS). Support for network-oriented filesystems such as InterMezzo (http://www.inter-mezzo.org) and Coda (http://coda.cs.cmu.edu) is already integrated into later 2.4 Linux kernels. New, web-based file-sharing mechanisms such as WebDAV (http://www.webdav.org) are easily integrated into existing Web-oriented environments, and can be mounted as though they were filesystems. The expanding dependence on networking as a basic tenet of computing today will only help popularize these newer, more powerful file-sharing mechanisms.
This article provides an overview of the benefits of distributed filesystems, discusses the most significant administrative issues in deploying and using distributed filesystems, and introduces the most interesting new distributed filesystems available for Linux today. Subsequent articles in this series will provide hands-on guidance for installing, configuring, and experimenting with some of the more interesting and useful of these networked filesharing mechanisms.