Some of us at work were talking over lunch about Google’s servers. There are apparently hundreds of thousands of them, and it’s well-known that they’re based on commodity x86 hardware. Otherwise, they’ve been pretty secretive.
The article came out on April 1st, so many are a little doubtful about its veracity, but its seems fairly believable. Apparently, the Google machines have integrated 12V batteries in lieu of UPSs, and the servers are hosted in shipping crates.
The Digg conversation also makes mentions of GoogleFS, their proprietary in-house filesystem that apparently makes it easy to stripe data across many servers. (Hadoop is loosely an open-source version of the same, though it’s not entirely the same.)
Edit: I included the link this time. After a while I started to doubt the veracity of this article. I’ll expand on some of my thoughts about why it seems odd in teh comments, but wanted to link to this Twitter post that seems to confirm the veracity of this article. Note that it’s dated April 2, which makes me think there’s better than a 50/50 shot that this is real. And this guy is either in on the prank, or corroborates that this was actually presented at a workshop.
So it seems like it may be real, but here’s why I’m skeptical. (Besides the date it was published.)
The sealed lead acid battery hanging off the back, for one. Besides looking like it’s held on with velcro, I’m curious about the logistics of it. Why have a couple dozen batteries in one rack, when you could have one big bank powering the whole rack? It seems like it’d be more efficient. And oops, I just invented the rackmount UPS.
The claim is that it cuts down on double-conversion: a normal UPS would pull in 120V (or 240V), step it down to 12V in the batteries, and then, to power the servers, convert it back to 120V (or 240V). Conversion either way is fundamentally inefficient. So Google’s cutting out the second conversion: 120V comes into the machine, and it gets stepped down to 12V, which can feed the battery and the motherboard.
I still think that it would make more sense to just put a 12VDC terminal on the back and have a bank of batteries per rack, though.
I also questioned the battery performance. A sealed-lead acid battery like that could maybe provide 75 Watts or so, which really isn’t much. But as the last link mentions, these aren’t meant like a home UPS: they’re apparently meant to allow power to be lost for a few seconds while the generators fire up.
The shipping crate idea is a neat one. It’s not unique (Sun has advertised the same thing for a while, though I’m pretty sure the marketing for it involved the Sun logo being plastered on a dumpster.) I don’t know my shipping crates that well, but it seems to me that it would be extremely tight. You have to account for cooling, too: ideally, you’d have really strong fans *behind* the servers, too. (Even with a relatively tame architecture of sparsely-populated racks, there’s probably a 30-degree difference between the front and back of our racks at work.)
I suspect that we’re going to start to see DIY projects of inserting batteries inside computers. (A lot like a laptop, actually…) The problem is that motherboards tend to have really complex power adapters. They’re pretty standard, but it’s not easy to just hook a battery in. Plus computers need several different DC voltages. Someone should make a power supply that makes it easy to wire in a battery, or a motherboard that just takes a single 12V supply and steps everything down.