Re: Oracle 10g hangs intermittently waiting for I/O
- From: Paweł Kotlarz <pkotla@xxxxxx>
- To: Rajeev Prabhakar <rprabha01@xxxxxxxxx>
- Date: Fri, 15 May 2009 23:34:47 +0200
Rajeev,
Oracle shows many sessions waiting for direct path read (temp). Tanel's
waitprof reports single events taking many seconds though most of
them are below 15ms.
On the OS level vmstat shows normal reading for some time and then
sessions in an uninterruptible sleep with no I/O taking place. iostat -x
and asmiostat (ML 437996.1) show specific volumes. Just after the
performance returns to normal these volumes show much greater queue
length (iostat) or much greater average read time (asmiostat).
I ran strace on a process servicing the session on which I used waitprof
earlier. It stops on a read call.
Currently I only know that the sysadmins found nothing in Linux logs and
on a 'system management page'. Unfortunately it is difficult to obtain
more information from them unless I tell what exactly to check...
Thanks,
Pawel
On 2009-05-15 22:32, Rajeev Prabhakar wrote:
Pawel,
What things have your Storage / Linux admins looked at ? Also, from
oracle's standpoint, what elements have you already looked at /
already ruled out (if any) ? Please share your inputs.
-Rajeev
2009/5/15 Paweł Kotlarz <pkotla@xxxxxx>:
Hello all.
I can isolate the problem to specific disks using iostat. These disks
are the same on a day the problem occurs but they are different on
another occurrance of the problem. Storage / Linux admins do not see any
problem on their side.
Thanks.
Pawel Kotlarz
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