I would like to build a server for a small company. For the time being, it should handle mostly data storage and data exchange. In a later phase it might also become a mail server, etc. However it will not be used for computational purposes and performance is not the number one criterion. It should be available 24/7, but latency due to disk spin-up is acceptable.
So a little NAS with RAID would probably be my best option here. And there are nice solutions out there: Current Qnap and Synology systems have many features and (especially the ones with ARM CPUs) have moderate energy consumption. The manufacturers state that energy consumption (4-bay RAIDs) are around 30-40 Watts when active and 12-20 Watts when idle (disk spindown).
I am aware that those NAS are probably the simplest way to achieve what I want. But I was wondering if you could go below and I would prefer to build my own system. My ARM-boards (Raspberry Pi, Beaglebone, etc.) consume 1-3 Watts when idle. So I was wondering if there wasn’t a way to design a server that comes closer to that figure. But I could not find any ARM-boards with RAID. This blog illustrates a little what I have in mind.
The requirements are:
- Energy-efficient CPU (probably ARM-based?)
- Energy-efficient power supply
- Energy-efficient disks (e.g. 2.5″ disks)
- RAID 5 (+hotswap)
- Gigabit LAN
Apart from choosing the right hardware, there are also software optimizations. For instance adaptive CPU frequency, disk spindown, etc.
Since there seems to be some doubt in the usefulness of my undertaking, I would like to highlight the importance of energy efficiency in the IT sector.
The question was marked as too broad, so I tried to narrow it down.
The comparison with light bulbs in the comments is… not ideal, because unlike light bulbs servers actually need to stay on 24/7.
The problem with building your own server is support–both for parts and for software. My recommendation would be to get the “greenest” standard hardware you can find–for the warranties–and then virtualize everything on it. I don’t think that that’ll get you a better footprint than one of those Banana Pi boards you mentioned, but as the number of servers goes up the power savings will increase, and it’ll be easier to build, support, and maintain.