Messages in this thread | | | From | "Hans-Peter Jansen" <> | Subject | Re: howto combat highly pathologic latencies on a server? | Date | Thu, 11 Mar 2010 17:58:49 +0100 |
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On Thursday 11 March 2010, 00:29:40 Dave Chinner wrote: > On Wed, Mar 10, 2010 at 06:17:42PM +0100, Hans-Peter Jansen wrote: > > > > The xfs filesystems are mounted with rw,noatime,attr2,nobarrier,noquota > > (yes, I do have a BBU on the areca, and disk write cache is effectively > > turned off). > > Make sure the filesystem has the "lazy-count=1" attribute set (use > xfs_info to check, xfs_admin to change). That will remove the > superblock from most transactions and significant reduce latency of > transactions as they serialise while locking it...
Done that now on my local test system, but on one of its filesystems, xfs_admin -c1 didn't succeed, it simply stopped (waiting for a futex):
Famous last syscall: 6750 futex(0x868330c8, FUTEX_WAIT_PRIVATE, 0, NULL <unfinished ...>
Consequently, xfs_repair behaved similar, hanging in phase 6, traversing filesystem... I have a huge strace from this run, if someone is interested.
It's an 3 TB Raid 5 array (4 * 1 TB hd) with one FS also driven by areca:
meta-data=/dev/sdb1 isize=256 agcount=4, agsize=183105406 blks = sectsz=512 attr=2 data = bsize=4096 blocks=732421623, imaxpct=5 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 log =internal bsize=4096 blocks=32768, version=2 = sectsz=512 sunit=0 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0
Luckily, xfs_repair -P finally did succeed. Phuah..
This is with: xfs_repair version 2.10.1.
After calling xfs_admin -c1, all filesystems showed differences in superblock features (from a xfs_repair -n run). Is xfs_repair mandatory, or does the initial mount fix this automatically?
Thanks, Pete
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