[Users] Force certain VMs to be on different hosts

[Ted Miller]

Scott

On 3/19/2014 10:30 AM, Scott Ocken wrote:
> Ted,
>
> Yes!  This is exactly what I was looking for.  I think you described it 
> better than I did.  This feature would be really nice.
>
> Thanks
> Scott
>
> Quoting Ted Miller <tmiller at hcjb.org>:
>
>> I think what the OP is asking for a designation as a "redundant group 1".  
>> He may have 10 hosts and 3 VMs in "redundant group 1". He doesn't care 
>> which hosts they run on, as long as they are three separate hosts.
>>
>> I can see this as being fairly widely applicable.  If you have multiple 
>> web servers for load sharing, you don't want them all running on the same 
>> host, because VM load is going to peak on them at the same times.  oVirt 
>> has no way of knowing that unless you give oVirt a hint to spread things 
>> around.  The web group might also want to split up the server that spreads 
>> the jobs around, and a database server used by all the web hosts.  I can 
>> see easily ending up with a group of 5 machines (3 web servers, a load 
>> sharing controller, and a database server) that you want spread across any 
>> 5 of the 15 servers in a cluster, because their loads are all going to 
>> spike together. You don't want oVirt having to try to migrate some of them 
>> during a load spike, because oVirt noticed that a host with 3 of the 5 is 
>> overloaded.
>>
>> Not my situation, but one I can see the usefulness of.
>> Ted Miller
>> Elkhart, IN, USA
>>
>> On 3/18/2014 11:54 AM, Meital Bourvine wrote:
>>> Hi Scott,
>>>
>>> Click on a vm
>>> Edit
>>> Show Advanced Options
>>> Host
>>> "Start Running on"
>>>
>>> ----- Original Message -----
>>>> From: "Scott Ocken" <scott at infobunker.com>
>>>> To: Users at ovirt.org
>>>> Sent: Tuesday, March 18, 2014 5:08:24 PM
>>>> Subject: [Users] Force certain VMs to be on different hosts
>>>>
>>>> Is there a way to have certain VMs to be on different hosts? (assuming
>>>> there are enough hosts)
>>>>
>>>> IE.  I have a db cluster of 3 VMs.  I would like each one to always be
>>>> on different hosts.  That way if a host goes down my db cluster is
>>>> still happy while migration happens.  Or if migration fails I am still
>>>> good.
>>>>
>>>> Thanks
>>>> Scott
>>
>> Ted Miller
It looks like the Negative Affinity/Anti-Affinity feature that Itamar Hein 
pointed out in his email, with a feature page at 
http://www.ovirt.org/Features/VM-Affinity includes what you are trying to 
do.  This is in 3.4, which in the QA process now.

Ted Miller
Elkhart, IN, USA