[ClusterLabs] RES: Performance of a mirrored LV (cLVM) with OCFS: Attempt to monitor it

[Carlos Xavier]

Hi.

I have been running OCFS2 on clusters for quite long time.
We started running it over DRBD and now we have it running on a Dell storage.
Over DRBD it showed a very poor performance, most because the way DRBD works.
To improve the performance we had to change the I/O Scheduler of the disk to "Deadline"

When we migrate the system to the storage, the issue show up again. Sometimes the system was hanging due to disk access, to solve the issue I changed the I/O Schedule To Deadline and the trouble vanished.

Regards,
Carlos.


> -----Mensagem original-----
> De: Kristoffer Grönlund [mailto:kgronlund at suse.com]
> Enviada em: quarta-feira, 25 de maio de 2016 06:55
> Para: Ulrich Windl; users at clusterlabs.org
> Assunto: Re: [ClusterLabs] Performance of a mirrored LV (cLVM) with OCFS: Attempt to monitor it
> 
> Ulrich Windl <Ulrich.Windl at rz.uni-regensburg.de> writes:
> 
> > cLVM has never made a good impression regarding performance, so I wonder if there's anything we
> could do to improve the4 performance. I suspect that one VM paging heavily on OCFS2 kills the
> performance of the whole cluster (that hosts Xen PV guests only). Anyone with deeper insights?
> 
> My understanding is that this is a problem inherent in the design of CLVM and there is work ongoing to
> mitigate this by handling clustering in md instead. See this LWN article for more details:
> 
> http://lwn.net/Articles/674085/
> 
> Cheers,
> Kristoffer
> 
> --
> // Kristoffer Grönlund
> // kgronlund at suse.com
> 
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