[dm-crypt] poor mysqldump performance
treed at ultraviolet.org
Fri Feb 24 00:59:49 CET 2012
On Fri, Feb 24, 2012 at 12:10:43AM +0100, Arno Wagner spake thusly:
> I notice that you are using a really, really old kernel.
> 2.6.18 is from end of 2006 or so. There were some
> performance issues with the dm-layer, they might just
> still be in this old version.
Yep. Unfortunately, this is in a big corporate production environment which is
way behind and difficult to arrange an upgrade. As you no doubt are aware,
2.6.18 is the standard kernel in RHEL/CentOS 5. We really need to move to 6 for
a lot of reasons but that is a long story.
> With 3.2.5 I basically see that IO is CPU limited
> or going at full speed if the CPU is fast enough.
> I have not tries a MySQL dump though, although this
> should just be standard disk accesses.
Are you aware of anything in 2.6.18 which might actually cause this? It is hard
to push for a serious upgrade to our standard database build on the basis that
it "might" fix the problem.
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