We are using vCenter v5.1 U2
We have 18 hosts in our dev cluster. We are a mixed environment of Windows and Linux. We recently decided to start testing some DRS rules that would keep all Windows guests on 5 hosts. We created a host group containing 5 of the hosts, and then created a VM group containing all of the Windows guests.
Next we created a DRS rule that said all of the Windows Guests should run on the "Windows Hosts". Within 5 minutes all of the guests had migrated to the correct hosts except 1.
This particular guest (A) has a Linux counterpart (B) - there is another rule stating these two machines must run on the same host. For whatever reason, every 5 minutes (indefinitely) they would both migrate to a new host but it was never one of the 5 hosts marked for "Windows Guests". I finally manually migrated Guest A to one of the proper hosts and eventually B followed and that was the end of that.
If I migrate A back out of the group, B will follow and both will start jumping around again but never making it back onto a proper host. If both A and B are on a Windows host (we don't care of Linux guests are on the windows hosts) and I migrate the Linux guest (B) off - it will eventually move back and join the windows guest (A). This tells me it is honoring the VM-to-host rule. But for whatever reason, once it is off of one of the proper hosts it can never find its way back.
We have two other guests (C and D) and they are also one windows and one linux guest with a VM-VM affinity rule. They behave the EXACT SAME WAY as A and B!
What is going on? Is this a bug? Can someone point me to some supporting documentation or an article that outlines a similar finding? I am having a hard time researching this one.
Thanks!
FWIW: we are in no way constrained for resources on any of the hosts in question. All storage and VLANs in use are presented and available to ALL hosts. The guests run fine when manually migrated to the proper hosts, they just cant find their way there via DRS.