A1000 I/O problems

From: stimmins@wiley.co.uk
Date: Fri Sep 13 2002 - 11:49:07 EDT


I have an anoying problem with an A1000 disk array attached to a fully
populated E450 running solaris 2.6 (Recommend patch cluster added a few
weeks ago). The A1000 has 8 36gb disks in a 7 disk RAID 5 configuration
with 1 hot swap spare. All other settings were left as the defaults when
creating the RAID.

A user is doing a VERY large tar to move files from 1 place to another
(something like 'tar cf - * | (cd newdir; tar xvf - ' ) and it is swamping
the RAID array. The user is using the system tar (GNU tar is available).
'top' is reporting an almost constant 30%+ iowait time on the CPU usage.

Sample out put from iostat:

root@development2# iostat -nx
                    extended device statistics
    r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device
    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 fd0
    0.5 1.0 4.9 13.9 0.0 0.1 3.3 49.0 0 1 c0t0d0
    0.4 0.2 3.9 1.5 0.0 0.0 6.3 53.2 0 0 c0t1d0
    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t2d0
    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t3d0
    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c1t6d0
   65.2 73.2 221.0 421.0 98.0 3.6 708.4 25.9 14 72 c2t0d0
    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
development2:vold(pid659)

This sort of operation has been done before without causing this problem,
and it used to complete much faster than it is doing now. The only recent
changes (last few weeks) to the system are the addition of the recomended
patch cluster.

Any ideas?

Thanks

---
Sean Timmins
Systems Administrator
John Wiley & Sons Ltd.
Baffins Lane
Chichester
West Sussex
PO19 1UD
Tel: +44 (0) 1243 770395
Fax +44 (0) 1243 770379
Mob: +44 (0) 7703 203546
******************************************************************************
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