So, I'm in the last couple of weeks of migrating my last farm to VI3 from ESX 2.5.x...
I migrated about 30 more VMs this weekend to a cluster of 9 existing host servers. I have DRS set for it to decide the best place to power on VMs...
As I powered on the VMs (this was over an entire day of migrating), I noticed that DRS kept chosing one of my host servers a lot more than the other host servers...
When the migration was done, I noticed that one host server showing yellow in Virtual Center... I went and looked at all the hosts...
Host 1 - 15 VMs
Host 2 - 15 VMs
Host 3 - 20 VMs
Host 4 - 21 VMs
Host 5 - 16 VMs
Host 6 - 18 VMs
Host 7 - 15 VMs
Host 9 - 14 VMs
Hosts 1-7,9 all had %CPU in the 26%-44% range, Host 8 was at 64%
Hosts 1-7,9 all had %memory in the 48%-72% range, Host 8 was at 82%
So why did DRS continue to power on VMs on Host 8 instead of using the other host servers?
I manually migrated some VMs off of Host 8 to distribute the load better... but I wish I knew how this worked and why it distrubuted the load that way.
Do you have any DRS rules set?
Yeah, I have a bunch of rules for the VMs that were already on those host servers... but nothing that should have applied to the 30 VMs I migrated over this weekend.
Do any of these rules contain more than two VMs (there's a bug with those rules)?
Try removing the rules or change them to only reference two VMs - this should start the automatical migration of VMs to other hosts.
I'm not sure if this bug affects rules that keep VMs together, but... I personally (just to be safe ) only use rules (regardless of the rule type) containing two VMs.