Hi,
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)
Let me start by asking you to check Cluster / Edit / Optimization tab to see whether you have memory overcommit enabled (it seems so). You can also select the host from the webadmin and you will see all the necessary information on the General subtab - most notably Physical RAM metrics and Maximum free memory available for scheduling. Those are a bit more accurate than the dashboard..
Currently I am only running 3 VMs with memory allocations as follows: Or 6144MB used by VM
Add 256 MB reserved by default for the host operating system (in /etc/vdsm/vdsm.conf) and 64 MB per VM for qemu overhead.
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
The engine takes both logical VM memory allocation (6GB) and the physical memory into account to make sure the VMs will have enough memory even in the future. So the displayed number usually does not resemble what you see directly on the host, because the VMs are not using their full share most of the time.
This is a bare minimal install of CentOS7 running only Webmin and oVirt.
Do you have all your VMs on the same host as the webadmin management console? That is usually a bad idea and we recommend using self hosted engine for this kind of setup (the webadmin running in a VM).
does a bare minimal install of CentOS really need 4-5GB of Ram to run?
Nope. It should be couple of hundred megabytes max for the host services. Check what `free` tells you too, I am pretty sure you will have a lot of cached pages there. This is all I can tell right now, the numbers from the Host / General subtab and the info about overcommit would shed more light on the topic. Best regards Martin Sivak On Thu, Aug 10, 2017 at 11:23 PM, Wesley Stewart <wstewart3@gmail.com> wrote:
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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