Let’s first find resource pools
[vSphere PowerCLI] C:\SysI> Get-ResourcePool Name Id ---- -- Classic ResourcePool-pool0 ESXi ResourcePool-pool1 Windows ResourcePool-pool2 vApps ResourcePool-pool3 Resources ResourcePool-ha-root-pool
Let’s check things in classic resource pool
[vSphere PowerCLI] C:\SysI> (Get-ResourcePool -Name classic).MemReservationMB 4304
Now what is 4304 MB. It is memory reservation for resource pool classic. So, how is this calculated ?
It is worst case allocation i.e. 2152 X 2 =4304
From where do we get worse case allocation ?
Worst case allocation = (memory or CPU) reservation + overhead reservation
= 2048 + 104
Where to find over head reservation for a virtual machine?
Go to resource allocation tab of the virtual machine.
See 104.00 MB encircled in Blue.
Now let’s go to root resource pool as shown in the picture below
Now Reserved Capacity is explained above, next thing remains is Overhead Reservation. Overhead Reservation is summation of all overhead reservation for all virtual machine
Available capacity = Total Capacity – Reserved Capacity
= 9843 – 5124