[ClusterLabs] Antw: [EXT] Problem with high load (IO)

[Ulrich Windl]

>>> "Lentes, Bernd" <bernd.lentes at helmholtz-muenchen.de> schrieb am 27.09.2021
um
12:37 in Nachricht
<323062346.20975278.1632739039598.JavaMail.zimbra at helmholtz-muenchen.de>:
> Hi,
> 
> i have a two-node cluster running on SLES 12SP5 with two HP servers and a 
> common FC SAN.
> Most of my resources are virtual domains offering databases and web pages.
> The disks from the domains reside on a OCFS2 Volume on a FC SAN.
> Each night a 9pm all domains are snapshotted with the OCFS2 tool reflink.

You have a very similar setup than we have, and we had an OCFS2 deadlock
during snapshotting (fix available for SLES15 SP2 now).

> After the snapshot is created the disks of the domains are copied to a NAS,

> domains are still running.
> The copy procedure occupies the CPU and IO intensively. IO is occupied by 
> copy about 90%, the CPU has sometimes a wait about 50%.
> Because of that the domains aren't responsive, so that the monitor operation

> from the RA fails sometimes.

Throttle the copying rate?

> In worst cases one domain is fenced.
> What would you do in such a situation ?
> I'm thinking of making the cp procedure nicer, with nice. Maybe about 10.

Nice won't help. See cgroups and ionice.

Regards,
Ulrich

> 
> More ideas ?
> 
> 
> Bernd
> 
> -- 
> 
> Bernd Lentes 
> System Administrator 
> Institute for Metabolism and Cell Death (MCD) 
> Building 25 - office 122 
> HelmholtzZentrum München 
> bernd.lentes at helmholtz-muenchen.de 
> phone: +49 89 3187 1241 
> phone: +49 89 3187 3827 
> fax: +49 89 3187 2294 
> http://www.helmholtz-muenchen.de/mcd 
> 
> 
> Public key: 
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