What happen really if Virtual Center goes down?

[vpalan]

What happen really if Virtual Center goes down?

if VC goes down, really DRS & HA won't work? and why?

[jayolsen]

DRS would no longer work. DRS depends on vMotion which requires vCenter to be up and running. As long as HA had already been configured then it would still work. It only requires vcenter for the configuration but not the operation.

[AWo]

First of all, vCenter won't be available anymore. Hard to belive but true.

You guests and hosts will continue to run normal.

DRS and HA won't work anymore as the cluster is build within vCenter and not on the ESX hosts. vCenter is the central instance which monitors the hosts and decides if and how to move the guests. Is that should work without vCenter there must be a process on all ESX hosts where they exchange information about their status and one of them must be the master who decides how to proceed. But that is not the case.

To avoid such an outage it is possible to have more than one vCenter installation.

AWo

VCP 3 & 4

Author @ vmwire.net

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[RParker]

First of all, vCenter won't be available anymore. Hard to belive but true.

So that explains why I couldn't connect anymore...hmmmmm..

[jayolsen]

HA should still work.

[AWo]

So that explains why I couldn't connect anymore...hmmmmm..

Yes, that's quite a mysterium, but after eliminating all other possibilities, that remains at last. Unprooven, but the last thing I could think of.

AWo

VCP 3 & 4

Author @ vmwire.net

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[nanair01]

I, myself do not think HA will work since when the VC goes down, the vpxa agents also stop their services and it will be hard for ESX Servers to communicate with each other.

If you find this post helpful/rectify your problem do not forget to award points

[weinstein5]

It is not the vpxa agent that is used for the communication in HA - there is a seperate agent that is used by the ESX host to communicate to other ESX hosts in the HA cluster including the master nodes that maintain thelist of VMs that are running and on which host they are running on

If you find this or any other answer useful please consider awarding points by marking the answer correct or helpful

[nanair01]

So that means VC Server is needed only for HA Confign and not for HA Operation right? Even if the VC Server is down, if the ESX Server configured in an HA cluster goes down, the VM's installed on that host will reboot in other hosts in cluster eh?

If you know any good documents which provide complete information about HA and agents involved in HA cluster, can you please post it right here? Thank you!

[weinstein5]

Sorry I do not have any documents but I know that is the way it works - the agent used to be AAH and can not remember if it changed in vSphere - but yes if VC is down HA will still work that is why you can run Virtual Center in a Virtual Machine in an HA cluster -

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[jayolsen]

AAM it was a Legato product.

[weinstein5]

Yes one of the benefits of both being owned by EMC

Sent from my iPhone

On May 4, 2010, at 3:17 PM, jayolsen <communities-emailer@vmware.com

[S_Grimbuhler]

Hi

1) The agent on the ESX in charge of HA is called AAM. It's in charge of communication between hosts (heartbeats, primary/secondary table, ressources info).

2) YES ! if vCenter is down, HA WILL work! it's designed for that. Otherwise, VMware wouldn't say "ok for a virtual vCenter". Reasons HA won't work are : Insufisent reserved ressources (be careful with admission control) ; All primary servers are down (be carful when HA accross multi-sites) ; VMs on un-shared Datastores (Do I forget something ?).

3) An excellent article explaining how HA work : http://www.yellow-bricks.com/vmware-high-availability-deepdiv/

Enjoy your virtual vCenter

Regards.

SG

[nanair01]

Thanks for the post SG, I highly appreciate it!

[vpalan]

Really good document SG. Thanks a lot...keep posting...

[S_Grimbuhler]

Give me points! give me points

==================

Senior Consultant

VCP 3-4 / VCI 3-4

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[vpalan]

Hey, Already done...

Regards,

Palani Vimal| System Engineer 

Global Technology Solutions Division    

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