For mirroring my backup drive, central data store for devices, music playing and a webserver for experiments, I'd like to run a small server at home. I want this server to be energy efficient, easy to modify, robust, silent and run customizable free software. It should have at least 500 GB of storage, but 1 or 1.5 TB is better. You can buy very low-energy computers such as the Fit-PC 2 (6 watt) or the Linutop 2 (8 watt). Energy costs for machines that run constantly can be roughly estimated by doubling the power draw in watt, so running a device that uses 8 watt constantly costs about 16 euro a year.
Until recently the computer I used most was a Dell X1 Latitude laptop. That machine is now 4.5 years old. At the time, I chose it because it is a laptop with no fan and hence very silent. It is still better than any atom based netbook. So I would like to use this laptop as a server. UPS and screen are integrated which is a nice plus. The machine has a 1.8" disk built in. It is not possible to replace it with a disk of at least 500 GB. I wanted to know the energy cost of adding more storage to the X1. So I did some power measurements with an 2.5" external disk (Toshiba, 160 GB) and a 3.5" external disk (TrekStore 500GB). I measured on my current main laptop, a Lenovo X200s too.
Lenovo X220s (console, idle, low brightness unless otherwise specified)
Dell Latitude X1 (console, idle, low brightness unless otherwise specified)
The 2.5" disk uses USB for power. The 3.5" disk has a separate adapter which is included in the power measurements. The device used for the power measurements is a DEM1379.