We have some virtual machines that have X memory allocated to them. This amount of memory is somewhat random. It was allocated to the machine because that was the amount of memory the physical machine had, because of a vendor recommendation, or because we threw out a best guess as to how much memory we thought the instance would require.
I understand the more memory the better, but I would also like to avoid over allocating memory to the VM when it isn't necessary. The memory could be better utilized by another machine.
What would be the best way to determine an ideal amount of memory per instance that is actually active and being used? Are there other counters we should be looking at in addition to page life expectancy? We have instance that have PLE's of 10k+ and others that have 100k+.
Any insight is much appreciated. Thanks, Sam