[ovirt-users] Re: What happens when shared storage is down?
On 7 Jun 2020, at 08:34, Strahil Nikolov
<hunter86_bg(a)yahoo.com> wrote:
На 7 юни 2020 г. 1:58:27 GMT+03:00, "Vinícius Ferrão via Users"
<users(a)ovirt.org> написа:
> Hello,
>
> This is a pretty vague and difficult question to answer. But what
> happens if the shared storage holding the VMs is down or unavailable
> for a period of time?
Once a pending I/O is blocked, libvirt will pause the VM .
> I’m aware that a longer timeout may put the VMs on pause state, but how
> this is handled? Is it a time limit? Requests limit? Who manages this?
You got sanlock.service that notifies the engine when a storage domain is unaccessible
for mode than 60s.
Libvirt also will pause a VM when a pending I/O cannot be done.
> In an event of self recovery of the storage backend what happens next?
Usually the engine should resume the VM, and from application perspective nothing has
happened.
Hmm thanks Strahil. I was thinking to upgrade the storage backend of one of my oVirt
clusters without powering off the VM’s, just to be lazy.
The storage does not have dual controllers, so downtime is needed. I’m trying to
understand what happens so I can evaluate this update without turning off the VMs.
> Manual intervention is required? The VMs may be down or they
just
> continue to run? It depends on the guest OS running like in XenServer
> where different scenarios may happen?
>
> I’ve looked here:
> https://www.ovirt.org/documentation/admin-guide/chap-Storage.html but
> there’s nothing that goes about this question.
>
> Thanks,
>
> Sent from my iPhone