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XFS FAQ

81.217.106.33 — Wed, 08 Sep 2010 05:41:01 GMT

←Older revision		Revision as of 05:41, 8 September 2010
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	Starting from kernel 2.6.35, you can try and then switch back. Older kernels have a bug leading to strange problems if you mount without inode64 again. For example, you can't access files & dirs that have been created with an inode >32bit anymore.		Starting from kernel 2.6.35, you can try and then switch back. Older kernels have a bug leading to strange problems if you mount without inode64 again. For example, you can't access files & dirs that have been created with an inode >32bit anymore.
		+
		+	== Q: Performance: mkfs.xfs -n size=64k option ==
		+
		+	Asking the implications of that mkfs option on the XFS mailing list, Dave Chinner explained it this way:
		+
		+	Inodes are not stored in the directory structure, only the directory entry name and the inode number. Hence the amount of space used by a
		+	directory entry is determined by the length of the name.
		+
		+	There is extra overhead to allocate large directory blocks (16 pages instead of one, to begin with, then there's the vmap overhead, etc), so for small directories smaller block sizes are faster for create and unlink operations.
		+
		+	For empty directorys, operations on 4k block sized directories consume roughly 50% less CPU that 64k block size directories. The 4k block size directories consume less CPU out to roughly 1.5 million entries where the two are roughly equal. At directory sizes of 10 million entries, 64k directory block operations are consuming about 15% of the CPU that 4k directory block operations consume.
		+
		+	In terms of lookups, the 64k block directory will take less IO but consume more CPU for a given lookup. Hence it depends on your IO latency and whether directory readahead can hide that latency as to which will be faster. e.g. For SSDs, CPU usage might be the limiting factor, not the IO. Right now I don't have any numbers on what the difference might be - I'm getting 1 billion inode population issues worked out first before I start on measuring cold cache lookup times on 1 billion files....

XFS Status Updates

Christian — Fri, 03 Sep 2010 21:27:23 GMT

url wikified

←Older revision		Revision as of 21:27, 3 September 2010
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	The XMLified versions of the XFS users guide, training labs and filesystem		The XMLified versions of the XFS users guide, training labs and filesystem
	structure documentation are now available as on the fly generated html on		structure documentation are now available as on the fly generated html on
-	the xfs.org website and can be found at~~: http://www~~.~~xfs.org/index.php/XFS_Papers_and_Documentation~~	+	the xfs.org website and can be found at [[XFS_Papers_and_Documentation\|Papers & Documentation]].

	== XFS status update for July 2010 ==		== XFS status update for July 2010 ==

XFS Status Updates

Hch — Thu, 02 Sep 2010 14:59:39 GMT

august update

←Older revision		Revision as of 14:59, 2 September 2010
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		+	== XFS status update for August 2010 ==
		+
		+	At the first of August we finally saw the release of Linux 2.6.35,
		+	which includes a large XFS update. The most prominent feature in
		+	Linux 2.6.35 is the new delayed logging code which provides massive
		+	speedups for metadata-intensive workloads, but there has been
		+	a large amount of other fixes and cleanups, leading to the following
		+	diffstat:
		+
		+	67 files changed, 4426 insertions(+), 3835 deletions(-)
		+
		+	Given the early release of Linux 2.6.35 the merge window for the
		+	next release fully fell into the month of August. The XFS updates
		+	for Linux 2.6.36 include various additional performance improvements
		+	in the delayed logging code, for direct I/O writes and for avoiding
		+	synchronous transactions, as well as various fixed and large amount
		+	of cleanups, including the removal of the remaining dead DMAPI
		+	code.
		+
		+	On the userspace side we saw the 3.1.3 release of xfsprogs, which includes
		+	various smaller fixes, support for the new XFS_IOC_ZERO_RANGE ioctl and
		+	Debian packaging updates. The xfstests package saw one new test case
		+	and a couple of smaller patches, and xfsdump has not seen any updates at
		+	all.
		+
		+	The XMLified versions of the XFS users guide, training labs and filesystem
		+	structure documentation are now available as on the fly generated html on
		+	the xfs.org website and can be found at: http://www.xfs.org/index.php/XFS_Papers_and_Documentation
		+
	== XFS status update for July 2010 ==		== XFS status update for July 2010 ==