Disk contention problems

From: Rob McMahon (Rob.McMahon@warwick.ac.uk)
Date: Fri Nov 23 2007 - 06:09:31 EST


I've got a machine here which has recently (over the last few weeks)
degenerated into being unusable at times. It's a V890 running Solaris
10, cyrus-imap (2.2.13) and squirrelmail. The mail partitions are on a
3510 FC, 500GB a piece, and RAID 5. The filesystems are UFS, and the
problematic one is 95% full. When it becomes unusable, iostat shows the
asvc_t times hitting 1000, 2000 or more. %b is pinned at 100% all the
time. %w hits 60% on the one partition. At quiet times I don't seem to
get better than:

    r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device
   71.8 258.8 618.7 4334.6 0.0 26.0 0.0 78.7 0 100
c6t600C0FF0000000000855613BE6F2D900d0
   35.6 129.6 322.3 2068.4 0.0 0.0 0.0 0.0 0 0
c6t600C0FF0000000000855613BE6F2D900d0.fp1
   36.2 129.2 296.5 2266.2 0.0 0.0 0.0 0.0 0 0
c6t600C0FF0000000000855613BE6F2D900d0.fp3

which is lower throughput than I'd expect. Truss shows creates, renames
and fdsyncs (which cyrus-imap seems to like using a lot) taking seconds.

sccli does show

sccli> show redundancy-mode
 Primary controller serial number: 8040592
 Primary controller location: Lower
 Redundancy mode: Active-Active
 Redundancy status: Failed
 Secondary controller serial number: 8009331
sccli>

and I have a call in about that with Sun, although they seem to be
arguing about maintenance levels as normal.

Really, I'm a bit desperate out here, and I'd like to hear any
suggestions or pointers to things I might not have thought about.

Any input gratefully received.

Thanks,

Rob

-- 
E-Mail:	Rob.McMahon@warwick.ac.uk		PHONE:  +44 24 7652 3037
Rob McMahon, IT Services, Warwick University, Coventry, CV4 7AL, England
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