Filesystems: Difference between revisions

Filesystems (edit)

Revision as of 15:41, 24 September 2009

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-Actually, ZFS is available on Linux too as a user space filesystem, and Sun are considering a kernel port:
+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).
-http://www.wizy.org/wiki/ZFS_on_FUSE
-However, I'm inclined to wait for btrfs (butter-fs). Here's a review of btrfs from an ex-ZFS engineer:
+== Ext3 ==
-http://lwn.net/Articles/342892/
+* 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)
-Oracle are working on a new generation NFS replacement designed specifically to benefit from some of the btrfs features:
+== Ext4 ==
-http://oss.oracle.com/projects/crfs/
+* fairly new in Linux kernel (since 2.6.27 or so)
+* becoming the default of new Linux distros
+* no 16 GB limitation
+* no compression and checksumming (data-integrity) features
-Here's an article one of the truely astonishing btrfs features: You can upgrade an existing linux file system to btrfs without destroying the existing fs or duplicating the data!
+== XFS ==
-http://btrfs.wiki.kernel.org/index.php/Conversion_from_Ext3 well, what are the alternatives?
+* SGI's filesystem that was ported to Linux some years ago
+* no 16 GB limitation
+* no compression and checksumming (data-integrity) features
-- ext3 does not support more than 16GB,
+== ZFS ==
-- ext4 does but is too young and lacks the features of zfs and btrfs
+* Sun's filesystem which is natively available on Solaris and OpenSolaris (both of which are freely available)
-- xfs also does but lacks the features of zfs and btrfs, and requires at least a good UPS. Bad XFS crashes are not unheard of.
+* there are ports of ZFS to FreeBSD and Mac OSX
-- don't know about jfs
+* the source code license of ZFS is incompatible with the GPL of the Linux kernel; nevertheless Sun is considering a kernel port (see http://www.wizy.org/wiki/ZFS_on_FUSE)
+* available as userland filesystem (ZFS-over-FUSE) on Linux;  installable packages are available e.g. on latest Ubuntu und Fedora (see http://www.linux-magazine.com/w3/issue/103/ZFS.pdf)
-All four do not support compression.
+== btrfs ==
+* latest addition to native Linux filesystems; stable version since 2.6.31 kernel (http://www.h-online.com/open/Kernel-Log-2-6-31-Tracking--/features/113671)
-It should be clear that a 100 TB filesystem requires some kind of backup. And tape backup itself is tricky and costly to get right.
+* a review of btrfs from an ex-ZFS engineer: http://lwn.net/Articles/342892/
+* you can upgrade an existing linux file system to btrfs without destroying the existing fs or duplicating the data: http://btrfs.wiki.kernel.org/index.php/Conversion_from_Ext3
-Currently, I would setup a Solaris fileserver with ZFS because ZFS is mature and the filesystem can be read by FreeBSD and Linux. A few months ago I tried an OpenSolaris installation CD and it worked like a charm.
+* http://www.h-online.com/open/The-Btrfs-file-system--/features/113738
-One possibility in Linux is ZFS over FUSE; this has a large number of advantages over other filesystems (except Btrfs) - see http://www.linux-magazine.com/w3/issue/103/ZFS.pdf . The article explains installation for Ubuntu. I must admit that I did not try it so far.
-The alternative would be Btrfs, see http://www.h-online.com/open/The-Btrfs-file-system--/features/113738 . This is available for latest Fedora and Ubuntu, is part of the recently released 2.6.31 kernel (http://www.h-online.com/open/Kernel-Log-2-6-31-Tracking--/features/113671), and will therefore in the future be available in all distros.