Monitoring host-ballooning activity
Ballooning is a part of normal operations when memory is overcommitted. The fact that ballooning occurrence is not necessarily an indication of a performance problem. The use of the balloon driver enables the guest to give up physical memory pages that are not being used. In fact, ballooning can be a sign that you're getting extra value out of the memory you have in the host.
However, if ballooning causes the guest to give up memory that it actually needs, performance problems can occur due to guest operating system paging.
Note, however, that this is fairly uncommon because the guest operating system will always assign already-free memory to the balloon driver whenever possible, thereby avoiding any guest operating system swapping.
In the vSphere Client, use the Memory Balloon metric to monitor a host's ballooning activity. This metric represents the total amount of memory claimed by the balloon drivers of the virtual machines on the host. The memory claimed...