On Fri, Sep 9, 2016 at 10:30 PM, Fernando Frediani <fernando.frediani@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...) 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