Skewed memory performance data

[gdesmo]

I have a vm that has been given 1 gig of memory. The windows 2003 OS is reporting 80% or so is always in use. But the VI performance graph is showing never more than 25% in use. I have attached some screen shots that should provide all needed info. The memory graph from VI is from the last week. You will see memory usage is never shown above 25%.

Any ideas why the large discrepancy? Thank you

[weinstein5]

What you are seeing is the power of Transparent Page Sharing - the vmkernel's ability to identify identical pages and store them one time saving memory - the guest o/s does not know it is going on so it reports the amount it thinks it is using - the perfomance graphs are showing what is acvtually being used by the vmkernel to store the vms memory

[gdesmo]

So the OS is almost maxed out on memory so I need to shutdown the vm bump it up to 1.5 or 2 gig? Even though the vm is not using as much mem on the host because of transparent page sharing. I have monitoring tools (netiq) within the OS that alert on memory usage at 80%.

The memory performance graph is accurtate on how much mem the vm is using on the host. Not how much mem is being used within the OS.

[weinstein5]

Yes you can increase the memory and see if there is any discernable improvement in performance - if there is not may be consider dropping it back - and yes that is what the graph is showing - use on the esx host -

[gdesmo]

So just to make sure I understand. The vm is memory constrained at this point. And data provided shows it is using most of it's granted mem.

Even though the vic is showing 25% (on average) of mem is used, this is only for the host.

I need to power down the vm and add more memory to it?

[weinstein5]

That is correct power down the VM and add memory - this will allow the guest o/s access to more memory - bu be aware that this might not improve performance -

yes the 25% referes to actual memory used on the host -

[doughavlik]

For what it's worth, when you are using NetIQ to monitor the guest OS for things like memory, but sure you are getting that data through the VMware ESX module rather than through the agent on the guest OS itself. The VMware module gets its data from Virtual Center, which will have the accurate metrics.

Doug Havlik

NetIQ Sales - Illinois

doug.havlik@yahoo.com

832.524.8016