Tom,

I'm pretty sure that such a counter doesn't exist. But it can be easily determined: just check the free memory on the host in either VirtualCenter or esxtop. Just as easily as saying "when the memory pressure approaches 1" one could say "when free memory approaches zero."

Details on memory stats on Memory Performance Analysis and Monitoring. You're specifically looking for the last entry ("free") on the PMEM row of the memory screen in esxtop or mem.heapfree.average in VirtualCenter.

Scott

I can give you some help there, too. The "how bad are things?" question can best be answered at by checking the swap rate. There's documentation on the esxtop and VirtualCenter counters that detail swap rates at Memory Performance Analysis and Monitoring. There's a good rule of thumb that if your host is swapping, your performance problems are serious.

Unfortunately, what we can't answer via counters is something that this idea of a "memory pressure" counter would fix. Knowing a ratio of needed v. present memory would tell us exactly how much memory needs to be added to the box to correct the problem. As this stand with swapping, the solution is to add a little more and check if swapping has been eliminated. If not, rinse and repeat.

Of course, you could determine exactly how much memory is needed by just adding up the amount of active memory for all VMs. But that's going to require some math on your part.