power and virtualisation

I have three (linux) servers in the office, stacked in the corner behind the desk.

One is my original server, an old P-75 that I bought from Secure Computing seven years ago. It’s been upgraded over the years; I added a new harddrive, a bit more memory, and I upgraded the CPU up to the awesome power of a P-133. These days, it’s stuffed in the corner as a firewall and my wife’s email server, and is otherwise consuming kWh and manufacturing dust-bunnies.

The second is the backup mailserver. A while back my 486-based backup box coughed up a harddrive-ball. In the search for a replacement, I found a whole machine for $10 more than the harddrive it contained, so I bought it. It’s a P-100 with 48Mb of memory and 1Gb of disk; more than enough for its single purpose. It used to be offsite, but I lost my free hosting when Baltimore became HP, so I took the backup server home, and moved the primary over to where the backup used to be.

The third is a machine I inherited from Baltimore; a Dell server, P-733 with 128Mb and a 40Gb disk. Recently I upgraded the OS to Ubuntu, which I love! Over the last couple of years this box has become the primary internal network server. I’ve added disk, memory, and CPU; moved services (email, house control, yadda yadda) from the old server.

Anyway, back to the subject. I was chatting with my brother-in-law before Christmas, and the topic of electricity came up. He has been aggressively replacing lightbulbs with CFLs, installing timers, and so on. His hydro bill was almost a third less than mine! Now, my kids are the ones who run into the house and turn on every light, and are atrocious at turning them off again; I’m sure that accounts for a significant portion of the difference. Until the recent window upgrade my house was a sieve, so I’m sure my furnace runs a lot more than his does. But nagging at the back of my brain for a long time was a comment I saw discussing computer power use. Estimating the power consumption of my servers suggests they account for somewhere between 10% and 15% of my total power consumption!

Obviously, It was time to do something. Solar panels were briefly considered; I have a beautiful expanse of southeast facing roof, but cost and ROI still aren’t there for southern Ontario. And besides, it should be relatively easy to reduce the power consumption of my computer network without inconveniencing anybody; if I start small, the task is likely to get finished. As an added bonus, reducing the server load means that the UPS will last longer during a power outage, and the room will be cooler in the summer.

Also just before Christmas, I read that Linksys had introduced a new model (version 5) of the WRT54G wireless gateway that did not run Linux. So when I saw a stack of version 4s on sale at Best Buy, I snagged one. I’ve moved e-mail to the more powerful server, and installed OpenWRT on the Linksys; ta-dah! One server eliminated.

Also before Christmas (coincidence? I think not!) we filled up the server disk (the new camera takes large pictures :-). I’m not quite ready to drop a wad of cash on a proper RAID array, but I did pick up another disk for the server.

Which brings me to the second half of the subject line. I’ve been a big fan of Vmware and related technologies for a long time. After listening to a seminar on Xen and virtualisation at work, it hit me; I could move the backup mailserver onto the P-733 box! So, that’s my next IT hobby project.

One more bonus? When I’m done, I’ll have enough spare hardware to start building a replacement for persephone (the main webserver)… (ducking)

posted at 7:49 pm on Sunday, January 29, 2006 in Personal | Comments (9)


  1. Jeff K says:

    Hm, 3 computers * 300W * 24h / 1000W/kW * 31 days * $0.08 kW/h = $53.50 / month. A bit high, I guess, but in the winter that power warms up the house a bit, saving on natural gas bills. I was surprised you didn’t do that all with 1 computer. I used to have many more natural gas appliances than I do now, because the price of gas keeps going up. 16 years ago, my dryer and oven were gas — for the last 7, I’ve been back on electric. I’ve been running CFL’s for possibly 10 years. Anyway, my DVD habit of $60/week is where I should look to save money. Which reminds me, “The Island” is on HD pay-per-view in 20 minutes…

  2. Harald Koch says:

    My computers are down around 75-100W under normal use. That 300W on the power supply is a maximum, not typical (but you knew that :). Also, two of these machines are old, and only have 200W power supplies :). Still, the ~ $20 / month adds up…

    More and more of our electricity is coming from natural gas, so I suspect that the gas – electric appliance tradeoff will swing back to gas soon.

  3. Reid says:

    I’ve been wondering about setting up a super-low-power (as in Watts) machine to be the only always-on server, effectively replacing both tnir (for web/email) and the G5 (for BitTorrent downloading). I am thinking of a hopefully cheap TransMeta chip or perhaps a Pentium M?

    Smaller, cooler, less power-consumptive would seem to be the watchword here. Of course, then there’s the DSL modem, which is always on as well, but there’s not much to be done about that.

    Are LCD monitors a lot lower power than recent CRTs? Or did all that Energy Star stuff actually make a difference?

  4. Harald Koch says:

    Monitors appear to be energy pigs when in use, but use almost no power on standby. Since I rarely use the console on my servers, that wasn’t an issue for me. Yes, LCDs are supposed to use a lot less power than CRTs.

    I found one site with some representative power readings; unfortunately, he doesn’t give hardware details: http://w9if.net/iweb/cpupower/.

    There’s some good low-power hardware out there these days; Shuttle PCs were the first, but some people have been poo-pooing them lately. There’s a whole site for VIA’s “EPIA” Mini-ITX boards at mini-itx.com ; I’ve read about people using both for MythTV boxes, so they have reasonable capacity with lower heat and lower power consumption.

  5. Mark says:

    A typical 17 inch CRT consumes about 75W with a mostly white background,
    65W with mostly black background and 0W in standby. A typical 15 inch flat panel
    consumes about 17 W.
    I was kind of shocked by the power consumption difference
    but the sticker price still keeps me away from LCDs.

    Ottawa City Hall rents out Kill-A-Watt devices so you can discover
    such trivia yourself. I’m in Toronto, so I just picked one up last
    time I was there for about $50 (ridiculously over priced but it’s worth a bit of fun).

    A VIA 10000CL mini-itx system uses 35 Watts when idle, hovers around 38-41 W
    when web browsing and playing music, but under load, can spike to 53 W.
    Those are all instant readings, after 2hours 30m of light use the cumulative reading was 0.09 kWh. So 36 W average.

    EPIA Center’s power simulator
    shows much lower numbers, 37 W peak and 23 W when idle (2.5 HDD and 40mm Fan EPIA CL10000).
    But the difference is likely because EPIA Center is quoting the consumption as measured post AC-DC conversion.
    My measurements are from the 113V wall socket.

  6. wjr says:

    The low-power always-on server is the approach we took – a VIA EPIA 800MHz processor (mini-ITX form factor motherboard), 120G disk. No display, keyboard or mouse – it just sits on a shelf. It’s our mail host, it serves http://www.flopcat.org, and also is the Slimserver music server. Very nice. It’s not fanless – there’s no CPU fan, but there are two small case fans that run constantly. I tried running it with them off, but the internal temperature got higher than I’d like. I also tried getting the disk to spin down, but I couldn’t stop it spinning up once an hour, which doesn’t sound like much but most drives are only rated for 10000 spinup cycles… I’m guessing it’s 25-30W constant draw.

    I also have one of the Linux-based WR54G routers acting as a firewall. The whole setup works nicely; once a week or two I back up the server’s drive to my desktop machine.

  7. wjr says:

    Oh yeah – and $CDN0.08 per kWh? Argh. We pay about $US0.19. That’s the marginal cost – the first 300ish per month are $US0.11, then the next 100ish are $US0.13, then it jumps to $US0.19. There are more brackets if you keep sucking down the power. Every marginal watt helps.

  8. Harald Koch says:

    FWIW, I’m not terribly happy about our cheap electricity. Sure it means my bills are lower, but it also means that investors are not willing to build the new power plants that we need, because there’s no profit in it. The doom-and-gloom people are predicting California-style rolling blackouts in a few years. It also makes alternate energy too expensive. For example, a personal solar power system in southern Ontario doesn’t break even until hydro gets up to around $0.12/kWh, last time I checked.

    On the other hand, we’re moving slowly to a competitive market. Commercial users (and distributors) already pay the floating market rate for electricity. Consumers still pay a fixed flat rate, and the province makes up the difference from general revenue. Anyway, at least for a while, electricity rates dropped; I just received a refund of the difference between what I paid and what the distributors paid for my electricity in 2004…

  9. […] It figures. After doing a bunch of work to move my backup mailserver to a virtual server, it worked fine for about 10 days, and then suddenly I was seeing no incoming email in the logs. This is a sign of a problem; even when the primary server is working, spammers are always connecting to the backup (in the hopes of getting past filters). […]

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