Openhab on Ubuntu 16.04 LTS - How much RAM?

i´ve bought a DELL T20 Server with Xeon E3-1225v3. I´m running ESXi 6.0u2 on it and now i want to install some virtual machines on it.

Can somebody tell me, how much RAM i should give a Linux VM only running Openhab 1.8.3? I will install Ubuntu 16.04 LTS Server. Is 2 cpu-cores and 2 GB RAM enough?

Ubuntu 16 server edition doesn’t take much ram at all. Openhab however, does run on Java which can be pretty resource heavy if you have a lot of stuff hooked up to it. The standard for most barebones servers now-a-days is minimum 4 gigs of ram, so I would go with that.

Resource: Systems admin and professional web developer

OpenHAB main process takes on the order of 0,5 GB. It runs well on Raspis (they have 1 GB). 2 cores, 2 GB is fine. Overprovisioning is no problem anyway if you use VMware unless you reserve them for the VM exclusively, which you shouldn’t.

I’m running on a similar setup. Xeon E3 1220v3, ESXi.
My default for Linux VM’s is one core and 512mb of ram, which I believe is what I gave OpenHAB too.
I haven’t had any problems at all.

I want to move over to Proxmox to take advantage of containers since I try to avoid Windows as much as possible. Unfortunately my storage VM, OmniOS, does not play nice with the q35 machine type for pcie passthrough.

I would definitely caution away from a single core. The os alone will contend on occasion with OH and cause it to be slow. I would personally want some multi tasking space there.

As mstormi suggests, for the most part, over committing cpu core to vm’s doesn’t really matter to vmware within reason. If you commit more core then a single proc has you can cause poor performance. Also, on a busy say quad core host, dual or single core vm’s will run faster than a quad core vm at the same time as the scheduler has to wait to schedule all 4 cores at the same time all while the single and duals are easier to fit in. Think of it like going to the restaurant with a party of 6. Sometimes you wait while parties of 2 slide past. Big tables are harder to find. I know the newer esxi versions are better with this, I just don’t know how much better. Old article but outlines what I mean.

Anyway, my point, I would go with 2 core and 1gb of memory for OH. If you add mysql or other services, jump to 2. Also, unless you are using that ubuntu box for anything other than OH, why not go Debian. Ubuntu is baggage on top of Debian. Debian will run smaller than Ubuntu. You can still install a desktop environment on Debian (pick xfce or something for extra small footprint) if you want to stay away from CLI.

Lastly, the good news, vmware and debian (ubuntu) are happy to adjust memory and cpu core on the fly. Feel free to start small and go bigger or start big and go smaller. Swap is the only part that is “hard[er]” to adjust on the fly. LVM will let you but I’m not certain it’s worth the hassle.