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Recovery planning for 2 node cluster + FOM

Dave Finch
Advisor

Recovery planning for 2 node cluster + FOM

I have 2 HP/Lefthand P4500 nodes in a cluster and a failover manager in the management group. In the event that a node fails AND the failover manager fails, the volumes would be offline even though one of the nodes would still have all the data. So, backing up the FOM seems to be the solution to enable us to recover quorum quickly. How often should the FOM be backed up?
6 REPLIES
Mark...
Honored Contributor

Re: Recovery planning for 2 node cluster + FOM

Hi
I do not think the back up of a FOM is an option.
Once a cluster has lost quorum you would not be able to but "another" FOM back in as only one FOM or a virtual manager are allowed per management group.
If you are running a two node cluster and you are concerned with loosing the FOM as well then maybe a VM is a better choice for you.
Mark...
if you have nothing useful to say, say nothing...
Dave Finch
Advisor

Re: Recovery planning for 2 node cluster + FOM

Mark, since the failover manager is a virtual machine, I could shut it down and copy the associated files (vmdk, vmx, nvram). I would do this at least once after the failover manager has been added to the management group. In the disaster scenario that I described, I wouldn't add another failover manager, I'd restore the backup and power it up. Will that same backup work in a week? month? year?
Dave Finch
Advisor

Re: Recovery planning for 2 node cluster + FOM

Mark, the objection to the virtual manager (VM) solution, is that it's a manual process. The failover manager works well in most failure scenarios. It's just this one catastrophic scenario that I'm trying to plan for.
Mark...
Honored Contributor

Re: Recovery planning for 2 node cluster + FOM

Hi Dave,
Why bother making a backup ?? I do not know or think that this is supported for a FOM - maybe somebody else knows ?? But I doubt if it is??
Why not just create another FOM ?? Then what you could do is remove the FOM on site 1 from the management group and then when complete add the FOM in from site 2 ???
It is not possible/supported to have two FOM's/VM's in a management group.
Yes I know that the VM is a manual process but at least you will be able to regain quorum!
As far as I know in your config of two nodes and a FOM if you lose a node and the FOM then the quorum will be lost = no access to your data. You will not be able to create or start a VM or add in another FOM to replace the one that is lost.
If you really need access to your surviving node/data then HP should be able to help you out.
Mark...
if you have nothing useful to say, say nothing...
Dave Finch
Advisor

Re: Recovery planning for 2 node cluster + FOM

"Why not just create another FOM ?? Then what you could do is remove the FOM on site 1 from the management group and then when complete add the FOM in from site 2 ???" It's not a multi-site san so there's only the Unassigned site. I'm assuming that a FOM maintains state information and that replacing it with a new FOM will not work. I'll try it and report back. If there's no state information maintained by a FOM, then restoring quorum will be really easy.
Mark...
Honored Contributor

Re: Recovery planning for 2 node cluster + FOM

Hi Dave,
When you remove a FOM it is removed completely from the management group. When you add in another one then that "new one" now resumes the FOM "duties".
Mark...
if you have nothing useful to say, say nothing...