vSphere "Host Failure" vs. "Host Isolation" -- and HA response

As I understand it, vSphere "Host Failure" happens when a host cannot communicate over management AND datastore networks, while "Host Isolation" occurs when either management heartbeat goes down or datastore heartbeat goes down for a host, but not both. Is this correct?

If host isolation is due to management network issues, I see no need to shutdown and restart VMs on a new host. However, in case of communication failure of a host to the datastore, restart of VMs is desirable. What HA response is recommended during Host Isolation? I seem to think Disabled is better if management troubles are more likely. Please advise. Thanks.

AKK
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AkulshAsked:
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
As I understand it, vSphere "Host Failure" happens when a host cannot communicate over management AND datastore networks, while "Host Isolation" occurs when either management heartbeat goes down or datastore heartbeat goes down for a host, but not both. Is this correct?

Almost...

VMware HA - Host Failure - Host stops functioning.

Heartbeats are sent via network, if none received, then datastore is checked, before declared a host failure.

VMware HA - Host Isolation - Host becomes network isolated

Network isolation occurs, when a host cannot receive traffic from the HA Agents on the management network, it then pings cluster isolation address, if no response, it declares Isolated.

If you have a good network design network isolation is very rare!
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AkulshAuthor Commented:
So Host Isolation has nothing to do with datastore heartbeats? In that case, I would let VMs keep running on the Isolated host while I fix the management network. In other words, HA response should be disabled.

Why would any one want to shutdown and restart VMs on a new Host when only management network is down and datastore connectivity is good? In other words, what is the use of other two HA response options for Host Isolation? Thanks.
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
So Host Isolation has nothing to do with datastore heartbeats? In that case, I would let VMs keep running on the Isolated host while I fix the management network. In other words, HA response should be disabled.

Correct, nothing to do with datastores.

and it's to stop trying to restart VMs, which would cause issues if already running.

Host maybe is faulty, and they want all VMs running on working hosts... your hosts could be using Management Network ?
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AkulshAuthor Commented:
Thanks.
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