[pve-devel] training question about HA && failback

Cesar Peschiera brain at click.com.py
Wed Jun 8 18:04:38 CEST 2016


Hi Alexandre

Restricted = The VM only can run in the permitted nodes (useful when some
nodes don't have access to the shared storage).
Nofailback = When a PVE node returns to life, the VMs that before was
running in this node not return again.

And answering at your question, for get the best strategy, i see that is
necessary two additionals directive:

"Priority" = That establish the priority of nodes for run a specific VM.
"Ordered" = Order of preference for run a VM.

For example (with 7 lines of text):
<failoverdomains>
  <failoverdomain name="VM-MailServer" restricted="1" ordered="1"
nofailback="1">
                <failoverdomainnode name="node-pve-1" priority="1"/>
                <failoverdomainnode name="node-pve-2" priority="5"/>
                <failoverdomainnode name="node-pve-3" priority="10"/>
  </failoverdomain>
<failoverdomains>

Of this mode, and without put the directive "nofailback", the VM will return
to "node-pve-1", or "node-pve-2" when them are alive, and the preference is
determinded by the directive "priority".
Tested in PVE 3.x with fence technology.

I hope I have been helpful.

Best regards
Cesar

----- Original Message ----- 
From: "Alexandre DERUMIER" <aderumier at odiso.com>
To: "pve-devel" <pve-devel at pve.proxmox.com>
Sent: Wednesday, June 08, 2016 11:06 AM
Subject: [pve-devel] training question about HA && failback


> Hi,
>
> my students of this week traning, have a question about HA and failback:
>
>
> We have 3 host :
>
> kvm1
> kvm2
> kvm3
>
>
> an HA group "kvm23" with kvm2 && kvm3
>
>
> We have a vm , with HA enable in group kvm23,with "nofailback" not
> enabled, "restricted" not enabled and vm is running on kvm3.
>
>
> kvm3 crash.
>
>
> the vm is restarted by HA to kvm2
>
>
> kvm3 is back online.
>
>
> vm does not failback to kvm3 ?
>
> The documentation said that it should failback to prefered node. But what
> is the prefered node ? any member of the group ?
>
> Students expected that vm fallback to last node before the crash.
>
>
> Regards,
>
> Alexandre
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> pve-devel at pve.proxmox.com
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