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2 Node VSA

Occasional Visitor

2 Node VSA

When setting up a 2 node VSA cluster it seems that FOM is only required for HA.

Without FOM what happens when a server fails? Do you need to manually start the VMs on the other server? Can anyone describe what happens when you have FOM and what happens when you don't?

Regular Advisor

Re: 2 Node VSA

The FOM is only to preserve quorum in the storage cluster.


If you were to lose one VSA in a two node cluster all of your volumes would be unavailable/disconnected. At this point both (or all) of your ESXi hosts would be disconnected from iSCSI storage, so HA would not be able to restart the virtual machines.


The FOM prevents or helps recover from the scenario described above.

Frequent Advisor

Re: 2 Node VSA

Also make sure FOM isn't running on the particular 2-node cluster's storage, else you'll end up with a chicken and egg problem.

Honored Contributor

Re: 2 Node VSA

exactly what they all said.


If the two nodes are on the same site, make sure its on a 3rd piece of hardware.  If you don't have an independent FOM and you have two nodes, you can actually end up LOSING system reliability simply because of that pesky quorum requirement.  A virtual manager is an alternative (however poor) when you absolutely cannot have  FOM and in that situation, when you have two nodes, the one without the virtual manager can fail without losing system availability, but if the one with the virtual manager fails you still lose system availability and will require manual intervention to regain quorum and LUN access.