Other File Systems Available to Fedora Core Linux

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Although ext3 is certainly an acceptable root file system, there are other alternatives. No operating systems can support as many root file systems as Linux, but you should be aware that every file system has its strengths and weaknesses. Some are better with small files, some are better with large files, some are better at writing data, and some better at reading data. Unfortunately, there is no one perfect file system. The following sections discuss some of the other common file systems available for use with Fedora Core Linux.

The Reiser File System (reiserfs)

The other popular journaling file system for Linux is the written-from-scratch Reiser file system, reiserfs. It is used primarily in the SUSE and Mandrake distributions, which support booting from a reiserfs root file system. reiserfs offers similar features to ext3, but there is no easy migration path from an already existing ext2 partition, as you learn to do in "Converting an Existing ext2 File System to ext3," later in this chapter. In the past, reiserfs didn't work well over NFS mounts, but recent versions of the nfsd daemon have fixed those problems. Fedora Core does offer reiserfs, but does not offer support for booting from it as the root partition file system, nor does it offer the choice to format non-root partitions as reiserfs during the installation process.

reiserfs is offered primarily for compatibility with existing reiserfs partitions you might want to access. Although the Reiser file system can be used as a root file system (meaning that Linux can be booted from a Reiser file system), Fedora Core has chosen not to support that option. The main problem is that reiserfs does not, at the time of writing, play nicely with SELinux and is therefore not recommended either by Red Hat or the NSA (SELinux's developers).

NOTE

The reiserfs file system has undergone a major update and release with Reiser4. The project, sponsored by The Defense Advanced Research Projects Agency (DARPA), aims to introduce improvements in a number of areas, such as maximum number of directories, files, links, sizes of individual files and size of the file system (nearly 18 terabytes). Other improvements include performance improvements and encryption.


JFS and XFS File Systems

Two commercial Unix file systems have been ported (rewritten) to allow them to be used in Linux. IBM has provided its Journaled File System (JFS) that is used with its commercial Unix named AIX. Silicon Graphics, Inc. (SGI) has provided its XFS file system used by its commercial Unix named IRIX. Because these file systems are generally suited for enterprise systems rather than home or small office systems, it seems likely that they are offered in Fedora Core Linux to ease the transition of IRIX and AIX users to Linux by eliminating the need for these users to reformat their very large file systems.

Beginning with kernel 2.6, XFS is fully supported in the kernel.

DOS File Systems

The extent of DOS file system support in Linux is often surprising to newcomers, but the DOS file system proved to be a viable option in the early years of Linux. Because Microsoft has been the dominant operating system on Intel computers, Linux has always worked toward coexistence with DOS.

Microsoft DOS and the consumer-oriented Windows operating systems use a file system known as FAT (File Allocation Table). FAT32 is the typical system used today. The number following the FAT name indicates the size of the space for naming address pointers; the more space, the larger a section of contiguous space can be identified and accessed. FAT32 is the most recent version of FAT, and it is backward-compatible with other versions of FAT. Older versions are not forward compatible.

The Fedora Core Linux kernel can access all versions of FAT formatted partitions (including floppy disks) using the vfat kernel module.

CD-ROM File Systems

If you use CD-ROM or DVD-ROM media, you need to understand a little bit about the file system and how it works with Linux. To the average user, the file system of a CD-ROM looks just like a native Linux file system. It is not the native file system, but the features of the Virtual File System make it possible for it to appear that way. The CD-ROM file system standards continue to evolve to accommodate new technology.

iso9660

The file system typically used on a CD-ROM is known as iso9660, the name of the standard that defines the format. Each operating system translates the iso9660 file system into the native file system of the operating system (with some restrictions). Several extensions have been created to address certain special needs. The Rock Ridge extension allows long filenames and Unix-like symbolic links. The Joliet extension allows Unicode characters and long filenames, useful when dealing with non-English languages. El Torito CDs contain a bootable image and, with a suitable BIOS, can boot an operating system from the CD.

Universal Disk Format

The Universal Disk Format (UDF) is the file system used on DVD discs. UDF has a number of built-in features such as allowing larger files, having improved file descriptors, and packet writing that the iso9660 file system cannot easily accommodate. The UDF format is the next step in compact disc technology.

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    Red Hat Fedora 4 Unleashed
    Red Hat Fedora 4 Unleashed
    ISBN: 0672327929
    EAN: 2147483647
    Year: 2006
    Pages: 361

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