shares

[MaxwellSmart]

I am unclear on the concept of Shares in resource pools.  I was hoping someone could help me clear that up.

Thanks.

Maxwell Smart.

Please Step under my Cone of Silence!

[Viperman]

Shares in resource pools operate in much the same way that shares on a stand alone ESx server work.  There are really three components of being able to limit access to resources in a resource pool.  The three components are Limits, Reservations, and Shares.  they work in the following manner.

Limits give you the maximum amount of a resource that you can use.  For example, if I set a limit of 512 megs of RAM on a VM.  It won't use more that 512 Megs because you put the limiter on it.  Almost like putting a rev limiter on a car, you can never go over that RPM no matter what.

Reservations give you a Guaranteed amount of a resource.  For example, on our last VM example if we set a reservation 256 Megs of RAM then you must have 256 Megs or more available to be able to give that VM.  If you don't have that much available you won't even be able to start the VM.  Even if the VM really only needs about 100 Megs of RAM, it must have 256 Megs available.

With Shares it is really used for the difference between the 256 reservation and the 512 meg limit.  If you have plenty of resources available then nothing really matters.  if you have limited resources, then anything above 256 must fight with other VM's kind of on a priority basis with the Vm that has the most shares will be the one that wins the battle.  If all VM's have an equal share value they will share the contends resources on an equal basis.

When VM's are part of a DRS cluster and the Resource pool is part of the cluster then DRS will move VM's around as needed using VMotion to be able to accomodate the resources needed by the VM's in the cluster.

Good luck on your upcoming movie!!