[one-users] Force VMs from specific template to deploy on single host only

[Carlos Martín Sánchez]

Hi,

On Mon, Sep 29, 2014 at 2:08 PM, Hamada, Ondrej <ondrej.hamada at acision.com>
wrote:

>  Hi,
>
> I’m trying to figure out how to force the virtual machines based on one
> template to deploy always together on a single node. A scenario:
>
>
>
> I have four nodes. I need to deploy five VMs related to each other. I want
> all the five to be deployed on the same host. Little bit later I need to
> deploy another set of five VMs. I want all the five of them to be deployed
> on a single node, but it should be different node then the preceding set of
> five VMs was deployed on.
>
>
>
> Speaking in terms of available scheduler policies is combination of
> packing and stripping. First use the stripping – find the node with highest
> count of available resources and then packing – deploy the VMs on same node.
>
>
>
> Is this even possible in OpenNebula?
>
>
What you describe cannot be done automatically in OpenNebula. You can make
use of the CURRENT_VMS [1] requirement variable, but this requires some
manual setup:

Let's say the IDs for group 1 are 10..14, and group 2 IDs are 15..19.

Set the SCHED_REQUIREMENTS to "CURRENT_VMS=10" for VMs 11..14, and
"CURRENT_VMS=15" for 16..19.
This will make each group to be deployed in the same host.

If you also set "CURRENT_VMS != 10" for VM 15, the second group will not be
deployed in the same host as the first one.

This can be done from the same template. Each time you instantiate, the
second param can be a path to an extra file that will be merged with the
existing Template [2].

Regards

[1]
http://docs.opennebula.org/4.8/user/references/template.html#requirement-expression-syntax
[2]
http://docs.opennebula.org/4.8/user/virtual_resource_management/vm_guide.html#instantiating-templates

--
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>
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