VMWARe - anti-affinity rules

[Mark Budman]

Hello,

I understand the concept of affinity and anti-affinity rules. However, I have a situation and wondering if it is possible to implement and how it can be done.

I have a cluster of 15 ESXi servers.

I have 3 database (db) linux virtual machines, db01, db02, db03 and 3 windows active directory ad) virtual machines, ad01, ad02, ad03

I want the 3 db machine machines to be on separate hosts, and the 3 ad machines to be on separate hosts.

I create a linux-db-anti-affinity rule on VM/Host rules for the db virtual machines, and repeat windows-ad-anti-affinity for the 3 ad virtual machines.

Fairly straight forward.

Now I would like to make groups of servers where each group cannot be hosted on the same host.

For instance, the situation I would like to set is that none of the 3 DB machines, say group-of-DB ( with members db01, db02, db03) can be hosted on a host that has any of ad virtual machines, say group-of AD (with members ad01, ad02, ad03) and vice versa.

Is it possible to create two  group of hosts and set  that any server within the first group (in this case db)  cannot be on a host where a server in the second group (in this case ad) resides?

Basically, anti-affinity rule preventing any server in 3 DB group (db01, db02, db03) cannot reside on a host that has servers from second group, 3 AD server (ad01, ad02, ad03)?

Is this at all possible?

If so, how can one implement or how can this be achieved?

Thanks,

Mark 

[Duncan Epping]

I read the question 3 times, and I am still not sure I understand what you are trying to do :-D

I am just wondering why are you trying to make it this complex? Why not just create regular anti-affinity rules?

[NickF123]

I'm not aware of any way to use VM Groups in affinity/anti-affinity rules. That said if you're only requirement right now (if I'm reading your post correctly) is none of the DB VMs should run on a host that has an AD VM, why not just create an anti-affinity rule that has all 3 DB VMs and all 3 AD VMs in it?

The only way otherwise I can see you can do it (with more combination flexibility) is by using host groups and having it so certain VMs can't run on certain hosts but personally I'd avoid that as you end up limiting the overall flexibility of the cluster and have to be careful when putting hosts into maintenance mode etc.

[CSpreha]

You can make an AA group with the 3 AD VMs, an AA group with the 3 DB VMs, then two VM groups with 3 in each and make an AA rule for those two groups.  As long as you have 6 or more hosts it will process and succeed.  If you ONLY have 6 hosts then you will not be able to patch as vLCM will not be able to find a host to move VMs where it does not violate your rules.  I have a similar setup on a cluster for some extreme performance testing of some VMs that we didn't want to overlap.

[Mark Budman]

Hello CSpreha,

Thank you for your reply. How does one make an AA rule based on groups?

Best,

Mark

[JimmyJack]

Mark, 

You are in a good position haveing 15 ESXi host and 6 servers to keep from running on the same host, so you easily accomplish this. Sounds like you have already made the groups to keep the DB servers and the AD servers on seperate ESXi host. All you need to do is to create a new group with all 6 VM's in this new group and then make an Anti-Affinity group that says the 6 virtual machines must run on different host.