Restrictions on Cluster Memory Capacity

[bernworx]

Is there a way to configure cluster to be more aware of memory usage? Like we can stop VMs from powering up if the memory usage gets too high, just like what Admission Control Policy do.

I think the policy will only work if the VMs within the cluster has reservations on CPU & MEM.

[LucD]

Thread moved to the vCenter community for more visibility

[frankdenneman]

Hi Bernworx,

There are a couple of admission controls active when using a cluster, DRS and host level admission control are a part of this as well. As the prime directive was considered to be over-consolidation, clusters and hosts allow the total memory and cpu virtual machine configuration exceed the total of available memory and cpu resources. When a reservation is set, it means that - under all circumstances - these resources must be kept available to that specific virtual machine or resource pool and thats why admission control is invented.

So in short, if you do not want to have the demand exceed the supply, either monitor the total configuration size of your virtual machines or set reservations.

I wrote a couple of articles about admission control:

http://frankdenneman.nl/drs/the-admission-control-family/

http://frankdenneman.nl/drs/drs-clusters-and-allocating-reserved-memory/

http://frankdenneman.nl/vmware/ha-admission-control-is-not-a-capacity-management-tool/

http://frankdenneman.nl/vmware/admission-control-and-vcloud-allocation-pool-model/