Exit Maintenance Mode and Enable HA no VM's move back to ESX Host - is this expected?

[macgreen]

Just updated 2 node ESX cluster. But what I am seeing is not what I would have expected. Is this the norm? Let me explain.

Settings:

I have DRS Automation Level set to Fully Automated and the Migration Threshold set in middle of Conservative and Aggressive

Under DRS all VM's Options are Fully Automated.

No Resource Pools configured. Just the default.

Scenario:

1. Disable HA on host1

2. Enter Maintenance Mode for host1

3. All VM's auto migrate to host2

4. Updates complete on host1

5. Exit Maintenance Mode for host1

6. Enable HA

My expectation was I would have expected DRS to start levelling VM's between the 2 nodes in the cluster - ie migrating some onto host1.

I see no DRS Recommendations either.

Is this all linked to Migration Threshold setting.?

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• ESX Server 3.5 U4 • VirtualCenter 2.5 U4 (VM) / MS SQL 2005 (VCDB,VUMDB) • SAN Infrastructure (FC) • NetBackup for VMware 6.5.3.1 • VCB 1.5

[squirrelking]

Short reply is "yes".

DRS only kicks in when there is contention in the environment.. even if you have DRS automation set to pretty agressive.. if all resources are being served, then DRS won't do much..

For your environment, I'd check the resources on the ESX host that has all your VM's.. if there is no contention, then the VM's won't migrate back to the host when it leaves maintenance mode.

I've been able to kick things into gear sometimes by adjusting the agressiveness on the DRS automation, but even that doesn't work all the time depending on the envrionment.

Hope it helps :smileyblush:

-Dennis

[crazex]

This happens to me, when I install updates to my hosts. Since DRS is based on active resources, not allocated resources, it doesn't move the VMs back to the other server, even though it seems like you've overloaded the other host. When the machines start to become more active DRS will move them accordingly. If you're really worried just manually migrate them to the other host.

-Jon-

VMware Certified Professional

[macgreen]

Thanks Dennis and Jon, when you get confirmation like this from other peoples environment it gives you more confidence about your own.

Yes, I agree with you Jon, I normally manual migrate some servers after the fact to balance the load myself.

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• ESX Server 3.5 U4 • VirtualCenter 2.5 U4 (VM) / MS SQL 2005 (VCDB,VUMDB) • SAN Infrastructure (FC) • NetBackup for VMware 6.5.3.1 • VCB 1.5

[Kahonu]

Aloha - How do disable HA for a particular host?? I ask coz whenever I enter MM on a server, no VMs migrate.

Mahalo, Bill

[macgreen]

Bill,

HA is disabled across the cluster. It cannot be disabled per ESX host.

The alternative would be to disconnect the ESX host.

Also, if your VM's are not migrating. check they do not have connected CD-ROM or floppy devices to ISO files etc.

And also check DRS settings for VM Options and how you have Automatic Migration per VM set and any VM Rules also.

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• ESX Server 3.5 U4 • VirtualCenter 2.5 U4 (VM) / MS SQL 2005 (VCDB,VUMDB) • SAN Infrastructure (FC) • NetBackup for VMware 6.5.3.1 • VCB 1.5

[Kahonu]

Aloha - Yes I know HA is en/disabled at the cluster level. I was only questioning what you said in the original post.

Re: my problem - nothing mounted and DRS is fully automated and agressive. Be that as it may, when I enter MM, it stops at 2% and won't continue till I manually VMotion all VMs off the host. Only when the last VM is off the host, does entering MM continue and complete.

Bill