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tomstanley1
Contributor
Contributor

Server 2012 R2 Memory usage

Hi everyone,

I've installed 2 x Server 2012 R2 instances (4GB RAM each) on an ESXi box with 8GB RAM and a modern Xeon processor.

I'm having a problem where, out of no where, RAM usage on the server (either one) will gradually increase to use 3.6GB and 4GB, and the system becomes very very unresponsive and slow. CPU usage is fine. Memory usage on the server shows that it is using all of the 4GB, but not anywhere near up to the 8GB. Is this a known problem?

Thanks,

Tom

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JarryG
Expert
Expert

If (as you wrote) your ESXi-box has 8GB physical memory, it does not mean it has 8GB RAM available for VMs. You have to substract 1 or 2GB for hypervisor itself. So if you created two VMs, each with 4GB and both are running, you are over-commiting memory. If both VMs really want to use 4GB, only part of that 2x4GB total is mapped to ESXi-host physical memory. Rest is handled by swapping (or memory compression, tps, etc).

So first of all, try to apply Rule No.1: do not overcommit ESXi-host memory, unless you really have to. In your case, substract memory used by hypervisor itself (iirc, it is about 1.5GB), and use only the rest for VMs (i.e. assign only 2x 3GB for VMs). Then check VMs for some time if they can live with this memory...

_____________________________________________ If you found my answer useful please do *not* mark it as "correct" or "helpful". It is hard to pretend being noob with all those points! :winking_face:
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