Well my windows server 2012 uses 1.2 gb running openhab and nothing else. I think 256 is too low based on the usage of my pc. Id get atleast raspberry pi 2 or 3. Or something around that. Not only for the ram but a slow cpu should make it less user friendly. Ive been looking at the orange pi zero for other stuff and i just dont think its fast enough or have enough ram. Might want a beefier orange pi
I’ve been running openHAB2 on a Orange Pi PC for about a year now which has 1GB ram. Top shows the java process using 40-50% of available memory. I think 256MB is a bit low.