I have a vCenter (6.0 U3b) with 3 clusters attached to it. Two clusters are 6.0U3 and one is 6.0U2.
On the 6.0U2 cluster, I'm unable to reduce memory reservations of VMs. The 6.0U3 clusters work fine.
There are no custom resource pools in the environment.
Essentially, setting the memory reservation higher than the current setting is fine, but then this becomes the new "limit" which it can't go below. So e.g. going from 0 to 2GB reservation, and then 2GB to 3GB, is fine, but going from 2GB to 1GB (or anything lower than 2GB) doesn't work.
By "doesn't work":
- vCenter through GUI and powercli shows correctly set memory reservation (1GB)
- Host through GUI (thick client connected as root) and powercli shows old memory reservation (2GB)
- VMX file shows old memory reservation (2GB)
- Host throws an error: Error available memory resources in parent resource pool are insufficient for operation: Group vm.012345: Requested memory minLimit <value> insufficient to support effective reservation <value>, where minLimit value is a little higher than what I'm trying to set the reservation to (1GB), and effective reservation value is a little higher than the old reservation (2GB)
If you try adjusting the reservation on the host itself it fails, complaining that the VM is managed by vCenter and adjustments have to be made there. I've even tried powering a VM off and setting the reservation with the same result. The only thing that seems to work is manually editing the VMX file to remove the reservation.
Through support we've tried removing "pools.xml" file and restarting management agents, this didn't affect anything. We have a recommendation to maintenance mode host, remove from cluster, re-add to cluster, though we haven't been able to try this yet.
The only other difference between this cluster and the others I'm aware of is the others are running NTP and hosts have correct time, while this cluster is not running NTP today and some of the times are off. But even for hosts which have current time this issue still remains.
I did find another communities post which sounds eerily similar but has no real resolution: Configuration Issues: "Unable to apply DRS... available Memory ressources in the parent ressource po...
Edit: to clarify, here is powercli output to demonstrate the problem.
Connected to vcenter:
PS> get-vm MyVM | Get-VMResourceConfiguration | select MemReservationGB
MemReservationGB
----------------
0
Connected to host MyVM is running on:
PS> get-vm MyVM | Get-VMResourceConfiguration | select MemReservationGB
MemReservationGB
----------------
112
Message was edited by: raidzero
