Going Green in the Home Datacenter
If you’ve been to my place, you know my basement sounds like a hair dryer. I have 5 machines running 24⁄7 most of the time. Noise and electric bills finally got to me, so I picked up a Kill-A-Watt to track power usage, per machine. What I found out is that having those machines on constantly accounts for 1⁄3 of my electric bill,almost 330 kilowatt-hours per month.
The 2 biggest hits towards power usage were # of drives, and processor type. More drives = more motors to spin. The most power-hungry drives were the Ultra320 SCSI drives, followed by PATA drives and finally SATAs. Processor power usage seemed to follow a slightly different curve, with a 2nd gen P4 using the most power, followed by P3s, Pentium Ds, and the Core 2 Duo.
Here is a breakdown of the machines, their electricity usage, and what I did to cut back:
Desktop: 68.4KWh/mo. In addition to being my main desktop, it is a primary fileserver with 4 drives, totalling 2TB of storage. Enabling suspend in Power Options and setting the timeout to 2 hours cut the idle usage to about 10 hours a day, or only about 31KWh/mo.
Torrent Server: 45.4KWh/mo. This is a secondary PC with no major file storage. I’m phasing out usage of this machine, reducing monthly consumption to about 10KWh.
Primary Fileserver: 112.3KWh/mo. This is the big guy that had to go. In addition to being the loudest server, it also chews up the most juice. After the new server (see below) is setup, this machine will be powered off for good. It has approximately 410GB of RAID5.
Secondary Fileserver: 42.5KWh/mo. Another fileserver which will end up combined with the primary into the new file server. It has about 430GB of RAID5.
Transcoder: 61.2KWh/mo. While it uses the 2nd most power of any of the servers, by combining the torrent server role with the transcoder, the power can be used more efficiently.
Shutting down the 2 fileservers and enabling power save options on the remaining machines would reduce power usage to approximately 102KWh/mo, or by about 2⁄3, but that would also mean sacrificing about 1TB of storage. Not something I can do. I needed to make up for that loss of storage without cutting my power savings too much.
I ended up getting a couple of 1TB drives to run in RAID1 and a new motherboard based around the Intel Atom, a low-power processor which can run with passive cooling. Low power and next to no noise. The results are much better than I expected: 28.1KWh/mo. Total electricity usage for all PCs and servers was reduced from 328KWh to 130KWh.
The new server buildtotaledabout $250. Recouping the cost of that with the savings will take about 1 year, but can be accelerated by selling off the old server hardware. It also means that 2 loud servers were shut down, replaced with a single passively cooled server. No more hair dryer in the basement.