Slashdot Mirror
XFS Merged into Linux 2.4
Alphix writes "As noted on KernelTrap Marcelo has merged XFS into 2.4 after a code review by Christoph Hellwig. The mail from Marcelo on LKML is here. Apparently it touched very little VFS code so people not using XFS shouldn't see any ill effects from this (it's even supposed to fix some VFS bugs).
XFS is described by SGI as '...a journalling filesystem developed by SGI and used in SGI's IRIX operating system. It is now also available under GPL for linux. It is extremely scalable, using btrees extensively to support large and/or sparse files, and extremely large directories. The journalling capability means no more waiting for fsck's or worrying about meta-data corruption.' Let the stability vs. new-features flamewar begin."
SGI has an overview on the XFS filesystem, just briefly pointing out some highlights. I also recall reading somewhere that it was possible (moreso than ext* filesystems) to undelete files on an XFS filesystem, although I'm skeptical.
Trolls lurk everywhere. Mod them down.
Here ya go.
Don't forget IBM's JFS, it's in 2.4 AFAIK, and the last time that there were benchmarks linked from slashdot, it actually seemed the best overall, even over the highly anticipated reiser4.
For all those that are looking for a filesystem comparison, I found this story to be quite interesting...or go here for the test details and results.
I use XFS on serveral different servers, mainly because I belive it performs better then ext3, or any other fs. Also because Alot of the servers I run are samba servers and the ACL support is built native into XFS. And last I looked ACL support was still not quite stable in ext2/3 it has been awhile so it could be stable by now.
Mandrake has offered XFS since at least 9.0, my first Linux distro. I've been using XFS (at the suggestion of my friend who helped with the install) for at least 6 months now, with only instance of a problem (not sure if it was a fault in the filesystem itself): lost or corrupted an inode or two, and fixed very easily once I knew what to do.
It works with both GRUB and LILO, is reasonably speedy, and has enormous partition and file size limits.
Count me a happy customer.
~~LF
Ext3 can grow or shrink an unmounted file system. XFS can grow a mounted file system.
Ext3 and XFS both have dump utilities, which many sys admins prefer for backup.
Ext3 supports three modes of journaling: writeback (risky metadata only), ordered (metadata only), and journal (all data). I believe XFS is comparable to ordered ext3.
Ext3 has been widely deployed on Linux, and it trivially reverts to ext2. The XFS design is mature, but its implementation on Linux is less proven.
Actually IMHO journalling on flash would be a bad idea. Most flash memories give you only about 100k write cycles before giving up the ghost. For mp3 players or digicams this is just fine. But, the point of the journal is that it is flushed to disk immediately on a write operation, so depending on usage you could wear out the memory cells that contain the journal file an order of magnitude faster, killing your flash memory REAL FAST.
Thoughts on tech, Software Engineering, and stuff
from the journals-are-for-girls dept.
:-)
Huh? I always thought it was diaries that were for girls... at least, that's what I told my friends when they made fun of my journal.
Laugh at stupidity: mod idiots +1 Funny.
(from http://www.sgi.com/software/xfs/overview.html)
Guaranteed Rate I/O
XFS is the only file system available that provides a guaranteed rate I/O system, which allows applications to reserve specific bandwidth to or from the file system. The file system can determine the available bandwidth and guarantee that a requested level of performance is met for a given time. This functionality is critical for media delivery systems such as video-on-demand or data acquisition.
Expanded Dump Capabilities
Unlike traditional file systems, which must be dismounted to guarantee a consistent dump image, you can dump an XFS file system while it is being used. The XFS dump utility, XFSdump, can dump an entire filesystem, a directory tree, or specific files. XFSdump is restartable, which allows a large dump to be spread over an extended period of time or to be resumed after a system restart.
-->tech stuff
Actually, this is not quite true. Most modern flash file systems are built upon a wear-leveling structure, so that rewrites to a particular sector are remapped uniformly over the remaining freespace. This prevents a single location in the flash from receiving too many rewrites. In practice, this makes the device last virtually forever. (Though knowing the wear-leveling pattern, you could probably force the worst case, in practice, this will not occur.)