[one-users] balancing VM placement

[Carlos Martín Sánchez]

Hi,

On Thu, Jul 31, 2014 at 7:47 PM, Mark Devlin <mdevlin at intelius.com> wrote:

> Greetings,
>
> Is there a way, using 4.4 or newer, for the scheduler to place VMs based
> on their names?


No, but you can set a specific SCHED_REQUIREMENTS and _RANK in the Template
[1]


>  Basically I want to spread a type of VM across as many hosts as possible,
> as long as the hosts have available resources for it.
>
> For example, if I have four hosts that have VMs and one that's empty, I
> don't want the five (web1-web5) VMs I'm about about to instantiate to all
> end up on that empty host.  I want one on each host.  However, if I start
> three more (web6-web8), it should place based on available resources.
>
> Hopefully that makes sense.  Thank you
>
> -Mark
>

That's how the scheduler works by default [2]. The policy is Striping, and
MAX_HOST is set to 1. The striping policy will try to send the VMs to the
host with less running VMs, but because of max_host = 1, only one VM will
be sent to the empty host in that scheduling cycle.

If you change the default policy, use SCHED_RANK = "- RUNNING_VMS" in your
Template.

Regards


[1]
http://docs.opennebula.org/4.6/user/references/template.html#placement-section
[2] http://docs.opennebula.org/4.6/administration/references/schg.html
--
Carlos Martín, MSc
Project Engineer
OpenNebula - Flexible Enterprise Cloud Made Simple
www.OpenNebula.org <http://www.opennebula.org/> | cmartin at opennebula.org |
@OpenNebula <http://twitter.com/opennebula> <cmartin at opennebula.org>
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