How to take over a VM from a "crashed" node?

[SusanneJ]

Hello,

I'm currently digging a bit into proxmox and there was a question, where I haven't found some dokumentation for...

I'm running a cluster with 2 nodes (no HA configuration) and all my vm-disks are on a shared storage (mostly qcow on nfs).
But if 1 node crashes, how could I restart the VM on the other node?

A migration would not possible I think? (Because the source-node is offline, or would it really be so simple?)

Would be nice, if you have an answer for me.

Thanks in advance,
Susanne.

 

[wolfgang]

Hi,
generally you can move the config and start!

But you have no quorum if one node is down.
so you can't move the config.

to do so you must change the quorum count.

this can be done with pvecm expected <count>.

 

[SusanneJ]

Hi,
to do so you must change the quorum count.
this can be done with "pvecm expected <count>".
...generally you can move the config and start!

Ah, that's great, thanks a lot. Tried, tested and worked (of course! ) (But now, one of my nodes is down and I'm not in the office to restart... but that's another story )

But please allow me another question:

could there be any negative sideeffects with setting the quorum-count to 1 in a 2 node cluster?

 

[wolfgang]

It is not recommended to let this on 1.
you should changer it back to the original value.

the quorum is to ensure, that a single host can't change the config.
this is important to prevent lost-updates etc.

http://en.wikipedia.org/wiki/Quorum_(distributed_computing)

 

[SusanneJ]

Thanks a lot!