If your cluster includes ESXi 5.0 hosts, you must avoid memory overcommitment. To prevent memory overcommitment in the VSA cluster, reserve all of the memory allocated to each virtual machine that runs in the VSA cluster.

After you upgrade to vSphere 5.1 and VSA 5.1, make sure to reverse these changes to enable memory overcommitment for virtual machines.

Power off the virtual machine before configuring the memory settings.


In the vSphere Client, right-click a virtual machine from the inventory and select Edit Settings.


In the Virtual Machine Properties window, select the Resources tab and select Memory.


In the Resource Allocation panel, set appropriate memory reservations.

To avoid memory overcommitment for VSA 5.0, select the Reserve all guest memory (All locked) check box.

To enable memory overcommitment for VSA 5.1, deselect the Reserve all guest memory (All locked) check box.


Click OK.

Repeat the same steps for all virtual machines that run in the VSA cluster.