[dm-crypt] poor mysqldump performance

Tracy Reed 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. 

Tracy Reed

More information about the dm-crypt mailing list