Filesystems

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Revision as of 16:27, 24 September 2009 by Kay (talk | contribs) (→‎btrfs)
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This page serves to give some information on possible filesystems for Linux machines, in particular those that may be used for very large filesystems (many TB). The list is sorted by age!

Ext3

  • fairly old, but well established and well behaved
  • does not support more than 16GB
  • does not support transparent compression
  • does not support checksumming (a data-integrity feature)

XFS

  • SGI's filesystem that was ported to Linux some years ago
  • no 16 GB limitation
  • no compression and checksumming (data-integrity) features

ZFS

  • Sun's filesystem which is natively available on Solaris and OpenSolaris (both of which are freely available)
  • (optional) transparent (gzip) compression (LZO compression available as patch)
  • atomic updates - means that the on-disk state is consistent at all times, there's no need to perform a lengthy filesystem check after forced reboots/power failures
  • background checksumming and self-healing for data integrity
  • Built-in stripes (RAID-0), mirrors (RAID-1) and RAID-Z (it's like software RAID-5, but more efficient due to ZFS's copy-on-write transactional model)
  • there are ports of ZFS to FreeBSD and Mac OSX
  • the source code license of ZFS is incompatible with the GPL of the Linux kernel, therefore only available as userland filesystem (ZFS-over-FUSE; see see http://www.wizy.org/wiki/ZFS_on_FUSE) on Linux
  • installable ZFS/FUSE packages are available e.g. on latest Ubuntu und Fedora (see http://www.linux-magazine.com/w3/issue/103/ZFS.pdf)

Ext4

  • fairly new in Linux kernel (since 2.6.27 or so); ext4 is based on ext3 (same developers)
  • becoming the default of new versions of Linux distros (Fedora, Ubuntu, ...)
  • no 16 GB limitation
  • no compression and checksumming (data-integrity) features

btrfs

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