A few notes on Guest Virtual Machine Memory Ballooning

Looking over some of my Windows 2008 R2 servers, I notice via Task Manager that their memory is 90%+ quite often.

Using Sysinternal’s RAMMap tool, I can quickly identify if this is due to ballooning.

Here’s a screenshot showing that 2.2GB of RAM is driver-locked (e.g., ballooned using the VMware Tools driver vmmemctl).

Using vSphere Client, I check to see the performance of this VM to confirm if this is ballooned memory and what the actual memory usage is currently.

You can see that it is indeed ballooning nearly 2GB of RAM on this VM and the Guest VM is actively using only a little over 1GB of RAM.

To control how much memory the VM will balloon, you can set sched.mem.maxmemctl parameter in the virtual machine’s .vmx configuration file. (Reference: VMware KB1003586MSDN Lock Pages in Memory VirtualLock)

The above KB mentioned is a good starting point for assisting troubleshooting Guest VMs that pin pages in memory (Lock Pages – using SQL with LPIM enabled?).

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