A common issue is where administrators intend to use resource pools strictly for organization and administration. They did not intend to affect the resource usage of the VMs, so each pool is set with default Shares, Reservation, and Limit for both CPU and RAM. The administrator utilizes the pool for administration purposes, such as to configure permissions and alarms, but the pools are not used to configure resource settings. This results in each pool having the same Shares for CPU and Memory, but if one pool contains twice the number of VMs than another pool, then each VM in the first pool is effectively guaranteed only 50% of the amount of CPU and RAM that is guaranteed to VMs in the second pool.
In this scenario, instead of configuring resource pools for administration and organization purposes, the administrator should configure VM folders. Permissions and alarms could be configured on each folder instead of on resource pools. If the administrator also plans to configure resource controls as well as permissions and alarms, then resource pools could be utilized instead of folders, but careful attention must be paid to setting the Shares, Limits, and Reservations. In this case, it may be simplest to manually configure the Reservation on each pool to guarantee the minimum amount of CPU and RAM that is expected to be required for the VMs in the pool. This approach ensures the pool gets a configured minimum of CPU and RAM without having to compete for it by applying Shares.