[Ocfs2-users] What could cause slow down betwen OCFS2 1.2.9 and 1.4.4

[Ulf Zimmermann]

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:thomaslau at esun.com]
> Sent: Friday, March 11, 2011 8:31 PM
> To: Sunil Mushran; Ulf Zimmermann
> Cc: ocfs2-users at 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 at 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
> ulf at openlane.com
> 
> 
> On Mar 11, 2011, at 14:32, "Sunil Mushran" <sunil.mushran at 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 at oss.oracle.com
> >> http://oss.oracle.com/mailman/listinfo/ocfs2-users
> >
> 
> _______________________________________________
> Ocfs2-users mailing list
> Ocfs2-users at oss.oracle.com
> http://oss.oracle.com/mailman/listinfo/ocfs2-users