[libvirt-users] Guests using more ram than specified

Dennis Jacobfeuerborn
Fri, 16 Jan 2015 12:33:19 -0000

Hi,
today I noticed that one of my HVs started swapping aggressively and
noticed that the two guests running on it use quite a bit more ram than
I assigned to them. They respectively were assigned 124G and 60G with
the idea that the 192G system then has 8G for other purposes. In top I
see the VMs using about 128G and 64G which means there is nothing left
for the system. This is on a CentOS 7 system.
Any ideas what causes this or how I can calculate the actual maximum
amount of RAM I can assign to the guests on a HV without overcommitting RAM?

Regards,
  Dennis