Tuning ZFS: performance anomaly with nocacheflush
- From: "Charles Schultz" <sacrophyte@xxxxxxxxx>
- To: ORACLE-L <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 18 Nov 2008 09:44:12 -0600
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 on Solaris 10, hardware is Sun T5240, EMC C3-80 SAN.
--
Charles Schultz
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