[ovirt-users] VMs paused due to IO issues - Dell Equallogic controller failover

[Michal Skrivanek]

> On 4 Oct 2016, at 09:51, Gary Lloyd <g.lloyd at keele.ac.uk> wrote:
> 
> Hi
> 
> We have Ovirt 3.65 with a Dell Equallogic SAN and we use Direct Luns for all our VMs.
> At the weekend during early hours an Equallogic controller failed over to its standby on one of our arrays and this caused about 20 of our VMs to be paused due to IO problems.
> 
> I have also noticed that this happens during Equallogic firmware upgrades since we moved onto Ovirt 3.65.
> 
> As recommended by Dell disk timeouts within the VMs are set to 60 seconds when they are hosted on an EqualLogic SAN.
> 
> Is there any other timeout value that we can configure in vdsm.conf to stop VMs from getting paused when a controller fails over ?

not really. but things are not so different when you look at it from the guest perspective. If the intention is to hide the fact that there is a problem and the guest should just see a delay (instead of dealing with error) then pausing and unpausing is the right behavior. From guest point of view this is just a delay it sees.

> 
> Also is there anything that we can tweak to automatically unpause the VMs once connectivity with the arrays is re-established ?

that should happen when the storage domain monitoring detects error and then reactivate(http://gerrit.ovirt.org/16244). It may be that since you have direct luns it’s not working with those….dunno, storage people should chime in I guess...

Thanks,
michal

> 
> At the moment we are running a customized version of storageServer.py, as Ovirt has yet to include iscsi multipath support for Direct Luns out of the box.
> 
> Many Thanks
> 
> 
> Gary Lloyd
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