Friday, September 30, 2011

vSphere 5: HA Demonstration

Some people asked me this question:

Will HA be activated if datastore is lost on a host due to iSCSI connection failure or FC connection on just one host without losing the host server from the management network?

Though I know the answer however I was curious myself and decide to find out by performing this on a iSCSI connection to see the results.

From my understanding, HA protects hosts failure however as long the host primary detection method (management network) is still alive, the host is considered alive in such, even though the VMs that the host is hosting is "gone" due to perhaps a nic failure for iSCSI connection or a HBA failure for FC connection, HA will not be activated even though datastore heartbeat (only in vSphere 5.x and its a secondary detection if primary failed) is lost.

I realize vCenter will initialed a migration of the VM however this will get the process halt.  We have to kill the process and wait for a timeout in order to take over the VM again else no options will be available for control.

In conclusion, HA protects hosts failure and not device failure on host.

Troubleshooting virtual machines that loses disk access

Update 14 Nov 2011
What if you meet with a power outage?  All hosts were shutdown?  The answer is posted on Yellow Bricks.

Basically if it was not powered off gracefully it will be power on the VMs base on the protected list after the election process of electing a Master is completed.


Anonymous said...

Nice article ..

Anonymous said...

Troubleshooting virtual machines that lose disk access

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