[ovirt-users] Storage latency message

[Nir Soffer]

בתאריך יום ה׳, 13 באפר׳ 2017, 16:03, מאת Chris Adams ‏<cma at cmadams.net>:

> Once upon a time, Yaniv Kaul <ykaul at redhat.com> said:
> > On Tue, Apr 11, 2017 at 3:57 PM, Chris Adams <cma at cmadams.net> wrote:
> > > I've been getting an occasional message like:
> > >
> > >         Storage domain hosted_storage experienced a high latency of
> > >         5.26121 seconds from host node3.
> > >
> > > I'm not sure what is causing them though.  I look at my storage
> > > (EqualLogic iSCSI SAN) and storage network switches and don't see any
> > > issues.
> > >
> > > When the above message was logged, node3 was not hosting the engine
> > > (doesn't even have engine HA installed), nor was it the SPM, so why
> > > would it have even been accessing the hosted_storage domain?
> > >
> >
> > All hosts are monitoring their access to all storage domains in the data
> > center.
>
> Okay.  Is there any more information about what this message actually
> means though?  Is it read latency, write latency, a particular VM, etc.?
>
> I can't find any issue at the network or SAN level, nor any load events
> that correlate with the times oVirt logs the latency messages.
>

Ovirt is reading 4k from the metadata special volume every 10 secods. If
the read takes more than 5 seconds, you will see this warning in engine
event log.

Maybe your storage or the host was overloaded at that time (e.g. vm backup)?

Nir


--
> Chris Adams <cma at cmadams.net>
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