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To continue with this question: Should be Vmware vCenter server high available?

According to the response there even if vCenter is down HA will continue to work.

So, if my vCenter is a VM, using the express sql edition in the same VM, and that VM is hosted in the same cluster it manages (and the cluster is setup for HA): Am I correct to assume that if the host that hosts the vCenter goes down HA will vmotion the vCenter VM to another host and it will continue to function?

BTW: my environment is small, two ESXi 5.0 hosts, with about 50 VMs, using iSCSI shared storaged for everything.

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To everyone that responded: thanks. I didn't expect such a quick responses. I wish I could flag more than one answer as "the answer" - I +1 everyone. BTW: yes, I mis-spoke, the VMs won't be vMotion (as they would have just crashed). –  rufo Dec 15 '12 at 23:18

4 Answers 4

up vote 4 down vote accepted

The vCenter VM won't be migrated to the remaining host, it will be restarted on the remaining host, so no vMotion will occur. It's also dependent on the VM Restart Priority. If the VM Restart Priority for the vCenter VM is disabled then it won't be restarted on the remaining host. If the VM Restart Priority is set to anything but disabled then the vCenter VM will/should be restarted on the remaining host. Note that the VM Restart Priority is dependent upon the available resources on the remaining host and the Admission Control setting (with or without DRS) so you want to set the vCenter VM restart priority to high to ensure that it is started on the remaining host.

Also note that a vMotion doesn't occur for the VM's on a failed host. VMware HA restarts the VM's on the remining host, it does not migrate them (with vMotion) to the remaining host.

Have a read here for more information:

http://pubs.vmware.com/vsphere-4-esx-vcenter/index.jsp?topic=/com.vmware.vsphere.availability.doc_41/c_useha_works.html

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You're partly right, except HA doesn't use vMotion - it simply restarts the VM on the pre-arranged host (if it's available).

My environment is far from small, we have many 24-32 host clusters, and we use this exact method for our various VCentres - it just works fine, although we use the 'full' MSSQL in cluster mode on a number of physical Windows boxes for our VC databases.

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Also, worth noting with 5.o, HA has been rebuilt with more methods of checking availability of VM's and hosts. For example, if it looses connectivity to a host via the management IP, it will check specific storage locations to see if the VM's are still running on the unreachable host and act accordingly.

I have one VM for vCenter running full SQL Server managing 8 hosts and 100+ VMs. I just make sure it has restart priority right after the domain controllers. HA is handled by the agent running on the hosts, not vCenter directly. So the hosts and HA continue to operate even without vCenter based on whatever the config was previous to vCenter going down.

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Good point about Host Isolation response. –  joeqwerty Dec 15 '12 at 17:48

Well, your system will continue running... This was answered in the question you linked to.

Nothing will "vMotion" to another host, but the already-configured HA services will restart the crashed/down virtual machines from the failed host on another host in the cluster.

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