Re: DRWR
Date: Fri, 9 Oct 2015 09:50:07 +0200 (CEST)
Message-ID: <2143302571.402017.1444377007674.JavaMail.open-xchange_at_app10.ox.hosteurope.de>
Hi guys,
just in addition to Moiz reply and as Michael is also using ZFS.
> Oracle asked us to get this percentage lower, so system admin added disks, as soon as the percentage was lower than 80%, log file sync issue
> resolved.
This is caused by ZFS fragmentation and the used copy-on-write approach. The whole behavior is also described in this paper in more detail - sorry that it is in german, but you can still interpret the graphs: https://www.yumpu.com/de/document/view/15431428/was-sie-von-oracle-uber-zfs-nicht-horen-werden-de-trivadis
We also discussed the ZFS stuff on OTN some time ago: https://community.oracle.com/thread/2604168
Best Regards
Stefan Koehler
Freelance Oracle performance consultant and researcher
Homepage: http://www.soocs.de
Twitter: _at_OracleSK
> Moizuddin Arshad Mohamed <moizarshad_at_gmail.com> hat am 8. Oktober 2015 um 23:00 geschrieben:
>
> Hi Michael,
>
> I have been in to the similar issue sometime back. Seems to be almost same issue. What file system are you using?
>
> We increased the SGA, DBWR and also redo logs were moved to a different disk, faster.
> We were using Veritas ZFS file systems. After trying all these, still log file sync issue continues......
>
> Later Oracle export from ZFS was involved, they applied some kernel level patches (not sure as I am not a sys admin) but prominently, the ZFS file
> system disk of pools was above 90% usage.... Oracle asked us to get this percentage lower, so system admin added disks, as soon as the percentage
> was lower than 80%, log file sync issue resolved.
>
> Hope this would help.
>
> Thanks,
> Moiz
-- http://www.freelists.org/webpage/oracle-lReceived on Fri Oct 09 2015 - 09:50:07 CEST