Filesystems provide a base for your files to bestored on the physical disk. A good analogy is that a disk is like thebuilding that houses your local library, while the filesystem is itsinfrastructure?the shelves that hold the books and the card catalogthat enable you to find a particular title.

Linux supportsmany different types of filesystems, each of which has its own internalstructure and access methods. To access a specific type of filesystem,Linux uses kernel software known as a driver that understands the internal structure of a specific filesystem.If you are trying to read a disk from another type of system, Linuxmight also need to load additional drivers to be able to interpret thedisk partition tables used by some types of disks and associatedfilesystems.

When you have created partitions, you must usuallycreate a filesystem in that partition to make use of the newlyallocated space. Many different types of filesystems are available forthis purpose, but this section focuses on types of filesystems that areavailable out of the box with SUSE Linux.

The most common and preferred filesystem used with SUSE is the Reiser filesystem (ReiserFS).ReiserFS was the first stable incarnation of a journaling filesystem onLinux. The development of ReiserFS was partly funded by SUSE as theyrealized that enterprise class storage (at least large storage pools)needed a journaling filesystem.

The choice of filesystemsprovided by Linux is quite large, and they all perform relatively well.A journaling filesystem is always recommended when quick restart timesand maximized data integrity are significant factors, and the ReiserFS,EXT3, JFS, and XFS are all excellent filesystems to consider.

In enterprise environments, optimizing data access and creation timesare especially significant features, with both XFS and JFS providingpotential performance advantages, especially when creating large files.For home users, getting the most out of your storage devices is often aprimary concern, in which case ReiserFS is a good choice.

If youwant to migrate existing EXT2 filesystems to Linux or are simplyconcerned about having the richest possible set of diagnostic anddebugging tools, the EXT3 filesystem is probably your best choice.

Thoseof you familiar with other forms of Unix will be expecting to find mkfsscripts to create new filesystems. As Linux is a form of Unix, it doesindeed use the notion of mkfs to create new filesystems. On Linuxsystems, the mkfs program is actually a wrapper for filesystem-specificversions of mkfs, which have names such as mkfs.ext2, mkfs.reiserfs,and so on.

When you execute the mkfs command, you must specifythe type of filesystem that you want to create using the -t (type)option, which the mkfs command then uses to locate the version of themkfs command that will create the specified type of filesystem. Thefollowing list shows the filesystem-specific versions of mkfs that arefound on a standard SUSE system:

# ls -1 /sbin/mkfs*
/sbin/mkfs
/sbin/mkfs.bfs
/sbin/mkfs.ext2
/sbin/mkfs.ext3
/sbin/mkfs.jfs
/sbin/mkfs.minix
/sbin/mkfs.msdos
/sbin/mkfs.reiserfs
/sbin/mkfs.vfat

Theutilities used to create EXT2 and EXT3 filesystems (mkfs.ext2 andmkfs.ext3) are actually hard links to the mke2fs utility (as is themkfs.ext3 utility discussed in the next section).

The mke2fsutility was written long ago, before the mkfs.filesystem-type namingconvention was developed. The mke2fs utility therefore takes differentoptions and behaves differently depending upon how it is invoked fromthe command line.

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