I am a little confused on why my CentOS box is using so much RAM. I currently have a small test setup which only has 12GB of ram total.

When I log into the administrative interface it tells me:

Memory

4.3

Available

of 15.5 GiB

Over commit: 39% (allocated 45%)

11.1 GB Used

Currently I am only running 3 VMs with memory allocations as follows:

Defined Memory:

1024 MB

Physical Memory Guaranteed:

1024 MB

Defined Memory:

3072 MB

Physical Memory Guaranteed:

3072 MB

Defined Memory:

2048 MB

Physical Memory Guaranteed:

2048 MB

Or 6144MB used by VM

If I SSH into my ovirt host, and run TOP and sort by memory, the top usage items are:

31896 qemu 21.5% 727:21.44 qemu-kvm

6008 qemu 14.6% 190:33.70 qemu-kvm

3019 ovirt 13.6% 35:47.64 java

5800 qemu 8.5% 784:26.88 qemu-kvm

2565 ovirt 3.9% 62:58.00 java

Everything else is pretty small compared, but for the OVIRT/QEMU we roughly get

Total: 62% = 7.45GB

So I am a bit confused as to the Ram being reported to me by the system (15.5GGB, but the system only has 12GB), and assuming OVIRT is using around 7-8GB, does a bare minimal install of CentOS really need 4-5GB of Ram to run?

This is a bare minimal install of CentOS7 running only Webmin and oVirt. I think there are several things I don't understand here, and I am quite new to oVirt and would like to learn, so please excuse my inexperience if this is a silly question!

Thanks either way, I am really happy I ditched my ESXi box :D