7GB of RAM not used by servers


New Member
Jan 29, 2019

I've 7 Linux VMs and 1 Windows VM on a 32GB server.
If I sum all RAM alocation (and not usage) and compare it with free -m from node, I see that there is more 7GB of RAM that is not used "anywhere" in the VMs. But I can't find from where it is comming from.

Is there any way to check where is this comming from and hopefully fix the issue?
I don't know if I understand your question correctly. Do you mean the sum of RAM usage as displayed within the VM's does not sum up to the RAM usage on the host? Note that you might have things like ZFS, caches, buffers and other things taking up memory on your host as well...
Hi Chris, Thanks for the quick reply.

That's exactly it. The sum of the allocated RAM (not usage RAM) is 23.35GB however I'me using more 7GB of RAM. I believe the SO can't take "that" much RAM.

I did the free -m and I'm not sure if it counts our the cache there. How can I find out?

Also, by default, if I hit 100% of RAM in the node, how will the VMs handle it? They will use disk as RAM, or...?

It is hard to tell what uses up your memory but you can try to find out via top/htop... If your host memory reaches it's limit, it will swap to disk.


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