If the host running vCenter fails, will VMWare HA still work?

Posted on 2014-04-16
Medium Priority
Last Modified: 2014-04-17
I have two hosts running ESXi 5.5, licensed for High Availability and vMotion.

I've tested vMotion back and forth between both hosts and all test ok.

I've also tested rebooting one of the hosts and the VMs on that host failed over to the other host, all test ok.

But what will happen when I reboot the host containing the vCenter Virtual Machine itself?  Will the failover of that VM and the other VM's on that host still work, if there is suddenly no vCenter running?

Question by:gateguard
LVL 42

Accepted Solution

Paul Solovyovsky earned 400 total points
ID: 40005865
HA will still work if vCenter is down

Assisted Solution

mlsbraves earned 400 total points
ID: 40005885
Yes HA will still work when vCenter is down.
LVL 126

Assisted Solution

by:Andrew Hancock (VMware vExpert / EE MVE^2)
Andrew Hancock (VMware vExpert / EE MVE^2) earned 400 total points
ID: 40005985
vCenter Server is only used to configure VMware HA, Once you have configured your hosts, vCenter Server installs an HA Agent (which is correclty called the FDM Agent - Fault Domain Manager Agent).

The FDM Agent, is responsible for monitoring and starting the virtual machines, when a host fails.

So, it does not matter, whether vCenter Server is Up or Down, control of VMware HA is controlled by the FDM Agents on all the hosts.

If you really want to know ALL the ins and outs in great details, Duncan Epping and Frank Denneman have now written three books on VMware HA and DRS Deepdive, which I recommend to ALL VMware Admins, and should be on your bookshelf!

Duncan's website is here, and is the most comprehensive VMware HA and DRS resource and explains all the basics, give it a read, and if you need to ask further questions please post back.

see here


I would recommend purchasing the HA DeepDive books!

Is the Best Resource for VMware HA and DRS.
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LVL 62

Assisted Solution

gheist earned 400 total points
ID: 40006608
1) vmware will evict machines as good as it can on e.g thermal or ram failure (that helps most people)
2) HA is between ESXis that check on eachother and if one is lost others try to get those machines back.
3) HA sometimes shots and misses and you end up with 2-3 ESXis in inconsisstent state and one VM unstartable
LVL 19

Assisted Solution

by:vmwarun - Arun
vmwarun - Arun earned 400 total points
ID: 40006694
vCenter is used only during the initial HA config. So HA will continue to work if vCenter is down.

Author Closing Comment

ID: 40007910
I tested it and it worked.  You are all right.  Thanks, all.

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