[Users] How to force VM's to run on different hosts?

[Itamar Heim]

On 07/31/2012 10:20 PM, Maxim Burgerhout wrote:
> Nice, thanks for the info. Can you give a hint of a time frame for the
> implementation? I'm not asking for dates or even version numbers, just
> something along the lines of 'short term', 'mid term', etc.

I'd go with mid-term.
(there is a POC patch for integrating drools which would allow you to 
write your own scheduling policies for something like that)
http://gerrit.ovirt.org/#/c/6574/

several thoughts here:
1. need to add positive/negative affinity fields to VM entity.
2. make the scheduling logic a supported interface for pluggable 
implementations
3. implement the drool implementation as a pluggable implementation.
4. support affinity based scheduling

#2 would allow someone to write their own scheduling logic in java code 
(well, maybe java wrapping/calling some other language).

#3 would allow someone to write their own scheduling logic using rule 
based language with drools.

#4 would mean you wouldn't need #2-#3 for this specific feature.


>
> Regards,
>
>
> Maxim Burgerhout
> maxim at wzzrd.com <mailto:maxim at wzzrd.com>
> ----------------
> EB11 5E56 E648 9D99 E8EF 05FB C513 6FD4 1302 B48A
>
>
>
>
> On Tue, Jul 31, 2012 at 3:19 PM, Itamar Heim <iheim at redhat.com
> <mailto:iheim at redhat.com>> wrote:
>
>     On 07/31/2012 04:07 PM, Maxim Burgerhout wrote:
>
>         Hi,
>
>         Can someone tell me whether setting positive and negative VM
>         affinity
>         rules will be at all possible with oVirt at some point in time,
>         i.e. is
>         this on the roadmap?
>
>
>     it is.
>
>
>         I need to be able to tell VM's to run on different hosts, spread
>         them
>         around, so to speak. For example, domain controllers would be
>         better off
>         running on as many different hypervisors as possible, the way I
>         see it.
>         That way, the failure of a single hypervisor has minimal impact
>         on the
>         infrastructure. I know there is a feature to pin VM's to a single
>         hypervisor, but that's not quite the same. I would like to group the
>         domain controllers and then tell them not to run on the same host as
>         other members of that group as much as possible.
>
>         The other way around would be nice as well: have several VM's
>         run on the
>         same hardware. For example, a three tiered web application would
>         probably perform better if the VM's are all on the same
>         hypervisor. I
>         know I could pin them all to the same hypervisor, but still:
>         that's not
>         quite the same. I want to be able to group the web app VM's and tell
>         them to try to run on the same hypervisors as the other members
>         of the
>         group, so they can move to another hypervisor as a group if the
>         need arises.
>
>         Apologies if this has been asked before or documented in some
>         place I
>         haven't looked yet.
>
>
>     two ways for you to do this today:
>     1. prefer/pin these VMs to different host
>     2. use two clusters and put them in different ones
>
>         Regards,
>
>         Maxim Burgerhout<mailto:maxim at wzzrd.__com <mailto:maxim at wzzrd.com>>
>
>
>
>
>
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