DRS groups and HA

[DanieleFiore201]

Hi guys,

i need to refresh my mind.

I need to ceate some DRS rules to keep VMs running on a bunch of specific hosts and that is fine.

What about HA ? will the DRS grups rules will be kept in case of a VM restart due to HA ?

I remember that in case of restart due to HA DRS rules are always checked before placing a VM on a specific host but i need to have this confirmed.

many thanks in advance,

Daniele

[mittim12]

I think after failover DRS would run and move all the VMs back to the host specified in the rules

[frankdenneman · Accepted solution]

Hi Daniele,

I've wrote a couple of articles on this topic, you might want to check them out:

http://frankdenneman.nl/2012/02/sdrs-anti-affinity-rule-types-and-ha-interoperability/

http://frankdenneman.nl/2010/12/vm-host-affinity-rules-should-or-must/

In short, HA is only aware of Required rules, (designated with Must run (not) on). HA is not aware of Should rules.

After HA failover, at the first time DRS is invoked (within 5 minutes) DRS detects the violation of the rules and will correct them first before computing cluster imbalance.

Regards,

Frank

[DanieleFiore201]

Hi Frank,

these articles are great and these were what i really was looking for!

many thanks,

Daniele

[keiooz]

Just a quick question. What does DRS actually do to your system?