Wednesday, July 23, 2008

Ubuntu Linux File Systems

File systems provide the structures in which files, directories, devices, and other elements of the system are accessed from Linux. Linux supports many different types of file systems (ext3, VFAT, ISO9660, NTFS, and so on) as well as many different types of media on which file systems can exist (hard disks, CDs, USB flash drives, ZIP drives, and so on).

Creating and managing disk partitions and the file systems on those partitions are among the most critical jobs in administering a Linux system. That’s because if you mess up your file system, you might very well lose the critical data stored on your computer’s hard disk or removable media.

Even though there are a lot of different file system types available in Linux, there are not many that you need to set up a basic Linux system. For a basic Linux system, your computer hard disk may contain only three partitions: a swap partition (used to handle the overflow of information in RAM), a boot partition that contains the boot loader and kernel, and a root file system partition. The boot and root file system partitions are usually an ext3 file system type.

The ext3 file system type is based on the ext2 file system type, adding a feature called journaling to its predecessor. Journaling can improve data integrity and recovery, especially after unclean system shutdowns. Time-consuming file system checks are avoided during the next reboot after an unclean shutdown, because the changes that occurred since the most recent write to disk are saved and ready to be restored.

Other type of file system:

ext3 - Most commonly used file system with Linux. Contains journaling features for safer data and fast reboots after unintended shutdowns.

ext2 - Predecessor of ext3, but doesn’t contain journaling.

iso9660 - Evolved from the High Sierra file system (which was the original standard used on CD-ROM). May contain Rock Ridge extensions to allow iso9660 file systems to support long file names and other information (file permissions, ownership, and links).

Jffs2 - Journaling Flash File System version 2 (JFFS2) that is designed for efficient operations on USB flash drives. Successor to JFFS.

jfs - JFS file system that IBM used for OS/2 Warp. Tuned for large file systems and high-performance environments.

msdos - MS-DOS file system. Can be used to mount older MS-DOS file systems, such as those on old floppy disks.

ntfs - Microsoft New Technology File System (NTFS). Useful when file systems need to share files with newer Windows systems (as with dual booting or removable drives).

reiserfs - Journaling file system that used to be used by default on some SUSE, Slackware, and other Linux systems. Reiserfs is not well-supported in Ubuntu.

squashfs - Compressed, read-only file system used on many Linux live CDs.

swap - Used on swap partitions to hold data temporarily when RAM is not currently available.

ufs - Popular file system on Solaris and SunOS operating systems from Sun Microsystems.

vfat - Extended FAT (VFAT) file system. Useful when file systems need to share files with older Windows systems (as with dual booting or removable drives).

xfs - Journaling file system for high-performance environments. Can scale up to systems that include multiple terabytes of data that transfer data at multiple gigabytes per second.

Besides the file system types listed in the table, there are also what are referred to as network shared file systems. Locally, a network shared file system may be an ext3, ntfs, or other normal file system type. However, all or part of those file systems can be shared with network protocols such as Samba (smbfs or cifs file system type), NFS (nfs), and NetWare (ncpfs).

Many available file system types are either not useful for creating new file systems or not fully supported in every version of Linux. For example, file system types such as minix (for Minix systems), befs (for BeOS systems), and affs (for Amiga systems) are mostly useful if you need to mount and access old backup media from those systems. Even popular file systems may not be fully supported. For example, reiserfs file systems isn’t fully supported, as of this writing, by the Kubuntu variant of Ubuntu.

Source Of Information : Wiley Ubuntu Linux Toolbox 1000 plus Commands for Ubuntu and Debian Power Users

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