the IO scheduler can be changed by adding "elevator=<name of scheduler to use>" to the kernel line in grub. But in EL5 you can do this also on the fly, by "echo <name of scheduler to use> > /sys/block/<devicename>/queue/scheduler"
> -----Original Message----- > From: Thomas Lau [mailto:thomas...@esun.com] > Sent: Friday, March 11, 2011 8:31 PM > To: Sunil Mushran; Ulf Zimmermann > Cc: ocfs2-users@oss.oracle.com > Subject: RE: [Ocfs2-users] What could cause slow down betwen OCFS2 1.2.9 > and 1.4.4 > > May I ask how you change these parameter ? > > Also, for a 90 percent read ocfs2, should I change to writeback as well? > -----Original Message----- > From: Ulf Zimmermann > Sent: 12/03/2011, 12:11 PM > To: Sunil Mushran > Cc: ocfs2-users@oss.oracle.com > Subject: Re: [Ocfs2-users] What could cause slow down betwen OCFS2 1.2.9 > and 1.4.4 > > > Another change we found is we used scheduler deadline, we are doing > downtime tonight to change scheduler and journal mode. > > > Ulf Zimmermann | Senior System Architect > OPENLANE, Inc | 2200 Bridge Parkway, Suite 202 > Redwood City, CA 94065 | (650) 412-4042 > u...@openlane.com > > > On Mar 11, 2011, at 14:32, "Sunil Mushran" <sunil.mush...@oracle.com> > wrote: > > > Verifying the journal mode is easy enough. Remount with data=writeback. > > It can be done one node at a time. > > > > But since you upgraded from 4.5 to 5.5, you may have to cast a wider net > > considering the entire kernel also changed. > > > > On 03/11/2011 02:22 PM, Ulf Zimmermann wrote: > >> We upgraded our production database cluster (6 node) from EL4 Update 5 > to EL5 Update 5, including upgrading OCFS2 from 1.2.9 to 1.4.4. > >> > >> We are now noticing slowdown of batch jobs in Oracle, while hotbackup > runs faster. One thing we saw is that journal mode changed from write-back > to ordered, as we don't specify journal mode during mount. Oracle sees this > as slowdown based on higher IO latency, going from 6-8ms to 13-15ms for > single block IO. Total IO throughput has dropped. > >> > >> Can this be caused by the journal mode being ordered? > >> > >> Ulf. > >> > >> > >> _______________________________________________ > >> Ocfs2-users mailing list > >> Ocfs2-users@oss.oracle.com > >> http://oss.oracle.com/mailman/listinfo/ocfs2-users > > > > _______________________________________________ > Ocfs2-users mailing list > Ocfs2-users@oss.oracle.com > http://oss.oracle.com/mailman/listinfo/ocfs2-users _______________________________________________ Ocfs2-users mailing list Ocfs2-users@oss.oracle.com http://oss.oracle.com/mailman/listinfo/ocfs2-users