[ovirt-users] Need some help understanding memory allocation

[Wesley Stewart]

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
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