Re: Tuning ZFS: performance anomaly with nocacheflush
- From: David Miller <David.J.Miller@xxxxxxx>
- To: sacrophyte@xxxxxxxxx
- Date: Wed, 19 Nov 2008 10:57:55 -0600
Hi Charles,
I asked one of the zfs experts and his comment was:
nocacheflush shouldn't be a problem since S10u5. If they are on
S10u4 or u3 (ack!) then they are probably hitting one or more of
other known problems, long since fixed.
So check what version of Solaris you're running and you may need to upgrade.
Regards,
Dave Miller
Charles Schultz wrote, On 11/18/08 09:44:
Good day list,
We are investigating why turning on the ZFS nocacheflush would affect a
simple (traditional) import so drastically. With the nocacheflush
default (0), we observe normal behavior. With the nocachflush set to 1,
we observe each db writer process suddenly having a LWP (Lightweight
Process) count in excess of 150 (some up to 175). This caused
significant kernel contention and slowed down the import significantly.
A truss on dbwr processes shows lots of sleeping and lwp_parking. I was
not able to find much relevant information on google or metalink for
tags "oracle zfs nocacheflush". Any ideas?
Oracle EE 10.2.0.2 <http://10.2.0.2> on Solaris 10, hardware is Sun
T5240, EMC C3-80 SAN.
--
Charles Schultz
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