Open Stack

2011/4/14 Sandy Walsh <sandy.walsh at rackspace.com>:
> Let's not confuse instance metadata with Compute Node Capabilities.
>
> When scheduling, the instance has not been created yet. We have to make decisions on where the instance will ultimately reside on a number of factors:
>
> 1. the capabilities of the host hypervisor (the Compute node)
> 2. the current load the host is under
> 3. the distribution policies of the customer (ie. "don't put all my instances on the same host/zone, etc")

I still question the usefulness of nr. 2. A host that is almost
completely idle right now might be under tremendous pressure a minute
from now and vice versa. Even if we had useful statistics (and trend
analysis) of the existing VM's on the host, we have no data at all on
the requirements of the instance we're about to launch.

It seems to me that the current load only affects the time it will
take to spin up the new instance, and as such says nothing about its
long term (or even medium or short term!) suitability as the new
instance's home.

-- 
Soren Hansen
Ubuntu Developer    http://www.ubuntu.com/
OpenStack Developer http://www.openstack.org/