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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."
Let the stability vs. new-features flamewar begin.
It's already been stable for years, since VERY early in the 2.4.x cycle. It's just a detail in the naming that makes it merged as part of 2.4.x itself.
Be careful those of you who still use lilo
Q: Does LILO work with XFS?
This depens on where you install LILO. For MBR installation: Yes. For root partitions: No, because the XFS superblock goes where LILO would be installed. This is to maintain compatibility with the Irix on-disk format. This will not be changed. Putting the Superblock on the swap partition is reported to work but not guaranteed.
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.
After patching every single kernel thats come out since the early 2.4s, I now have a kernel that I don't need to patch. WOW, about darn time!! Perhaps I'll even get lucky enough that RedHat and others that do not support XFS yet will build it into their kernels. That will make MY life easier, and updates go faster.
We chose XFS after lots of serious testing. It beat all comers at the time and we've been using it ever since. The only downside to XFS is file deletion times are a bit long, especially compared to Reiser, but when you have a server that is uner HEAVY load (Databses, mail servers) and with LARGE files (log server) nothing beats XFS.
Thanks guys, this is one of those merges that has made me estatic!
Angry People Rule
"Science is about ego as much as it is about discovery and truth " - I said it, so sue me.
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.
Extended ACLs, btree filesystem structures to facilitate huge files, fast sparse files, large directories, fast deletes, and a couple other niceties that would have required huge functional changes to ext2/ext3 to implement. It's also completely 64-bit clean, as it has from its conception.
The btree-based storage structure is already employed by reiserfs in a similar manner, but XFS' implementation has been stable (used in IRIX) for quite a bit longer.
Yes.
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
http://epoxy.mrs.umn.edu/~minerg/fstests/results.
Of course your mileage may vary but I generally got results consistent with those cited.
My own experiences (I have used both reiserfs and xfs with 2.4.20 kernel:
You can defy gravity... for a short time
dump is not recommended with ext2 or ext3 because it opens the block device directly which bypasses the page cache and can give you corrupt data if there are dirty pages that havn't been flushed to disk.
I'm not sure if xfsdump is any smarter about it because of the DMAPI stuff available, but I'd be carefull.
(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.)
Plus its sure to piss SCO off :)
;-)
That is not the half of it. You see-- Hellwig is a former SCO employee who when he worked there, worked with IBM closely on their port of JFS to Linux. He was also heavily involved in the SMP development process too. Just do a search for his name and SCO and Caldera on your favorite search engine. I think it will be hard for him to avoid a deposition
Now he works for SGI.
LedgerSMB: Open source Accounting/ERP
This is not an endorsement of JFFS, it's just an example of a flash friendly journalling filesystem. (I have not used it - it may be the best filesystem ever, I don't know).