[Users] Force certain VMs to be on different hosts

Ted Miller tmiller at hcjb.org
Wed Mar 19 09:45:49 EDT 2014


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
>>
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>> Users at ovirt.org
>> http://lists.ovirt.org/mailman/listinfo/users
>>
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-- 
"He is no fool who gives what he cannot keep, to gain what he cannot lose." - - Jim Elliot
For more information about Jim Elliot and his unusual life, see http://www.christianliteratureandliving.com/march2003/carolyn.html.

Ted Miller
Design Engineer
HCJB Global Technology Center, a ministry of Reach Beyond
2830 South 17th St
Elkhart, IN  46517
574--970-4272 my desk
574--970-4252 receptionist



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