[ovirt-users] Minimal resources for Engine

[Yedidyah Bar David]

On Fri, Sep 9, 2016 at 10:30 PM, Fernando Frediani
<fernando.frediani at upx.com.br> wrote:
> Hi there.
>
> I was reading this interesting URL someone just sent a while ago regarding
> hyperconvergence topic
> (https://www.ovirt.org/blog/2016/08/up-and-running-with-ovirt-4-0-and-gluster-storage/)
> and found the point about the optimal amount of resources for a Engine -
> 16GB of RAM.
>
> I just wanted to ask what component or feature eats up so much memory for
> that amount be the recommended. Or is it just in a hyperconverged scenario ?

The engine itself needs quite a lot of memory.

>
> Are there any components that can be optional that can reduce the amount of
> memory needed to run the Engine ?

DWH and postgresql need quite a lot too.

In principle you can run each of: engine, dwh, engine's db, dwh's db
on its own machine, total of 4 machines.

Also please note that the "minimum" according to engine-setup (and
elsewhere) is 4GB, and that this greatly depends on your setup's size
and use patterns/flow (e.g. how often do you ask the engine to do
something compared to the engine most of the time just monitors stuff
etc).

>
> Also with if the Data Warehouse runs in a separate host what would be the
> reduction in resources consumption, specially memory ?

I am not aware of actual semi-accurate measurements done recently,
and I guess most people don't bother because memory is cheap these
days.

Personally I usually run my engines on VMs with 2-4GB RAM, and
never had problems. These are used only for testing/development
and not for real work. I am also aware of engines on machines
with 8GB RAM, managing 100-200 VMs with no problems.

See also:

https://bugzilla.redhat.com/show_bug.cgi?id=1185411
https://bugzilla.redhat.com/show_bug.cgi?id=1329119

Bottom line:

If you don't care much and have a few tens/low hundreds VMs,
just use 8-16GB.

If you do care, and/or have much larger setups, either separate
the services to different machines, or actually do some tests
(and publish the results!), or both.

Hope this helps,
-- 
Didi