I work with a Managed Service provider and we sell virtual servers as a service to our customer installed base. All resources are sold incrementally for CPU and MEM. We do not currently have options for selling priorities via the use of shares or greater reservations per VM. We built our cluster with oversubscribing resources in mind and thus we created reservations per VM of only 50% of actually provisioned resources. We are finding that the actual VM useage rates are much less than 50% but our reservations have now exceeded our adminision control limits limiting our DRS and upgrade process for evacuating a Host by moving all VMs to other Host in a cluster. We have to remove the reservation to complete Vmotion and Host evacuation drills, even with allow admission control to be exceeded.
My question is within an environment in which all guest are to be treated as equals regarding the ability to access CPU and Memory resources does it even make sense to create reservations per VM? With these circumstances are reservations still a way to provide gaurenteed resources to VMs and maybe we should look to reduce the res to 25%??
thanks
