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A Look At the Workings of Google's Data Centers
Doofus brings us a CNet story about a discussion from Google's Jeff Dean spotlighting some of the inner workings of the search giant's massive data centers. Quoting:
"'Our view is it's better to have twice as much hardware that's not as reliable than half as much that's more reliable,' Dean said. 'You have to provide reliability on a software level. If you're running 10,000 machines, something is going to die every day.' Bringing a new cluster online shows just how fallible hardware is, Dean said. In each cluster's first year, it's typical that 1,000 individual machine failures will occur; thousands of hard drive failures will occur; one power distribution unit will fail, bringing down 500 to 1,000 machines for about 6 hours; 20 racks will fail, each time causing 40 to 80 machines to vanish from the network; 5 racks will "go wonky," with half their network packets missing in action; and the cluster will have to be rewired once, affecting 5 percent of the machines at any given moment over a 2-day span, Dean said. And there's about a 50 percent chance that the cluster will overheat, taking down most of the servers in less than 5 minutes and taking 1 to 2 days to recover."
I understand distributed computing and I understand distributed searching. But the fact of the matter is that at some point at the top of the chain, you're usually transferring very large amounts of data--no matter how tall your 'network pyramid' is. The coding itself is no simple feat but I have heard rumors that Google was building their own 10-Gigabit ethernet switches since they couldn't find any on the market. You'll notice a lot of sites are just speculating but it certainly is a nontrivial problem to network clusters of thousands of computers with more than 200,000 in the whole lot and not require some serious switch/hub/networking hardware to back it.
My work here is dung.
Interesting, but I would probably venture a guess: never.
Unless of course you are talking about P2's and ISA's, and its not a matter of "reliability" I dont think, it could easily be argued that a $200 [component] is just as reliable as a $500 [component] I think mostly what they are doing, is buying 3 of something cheaper, instead of one of something greater.
Component A:cheaper, less cutting edge (generally more reliable)
Component B: Has 3 times the power, 3 times the load, costs 3 times as much.
If a single component A fails, there is still 2 running (depending on the component) and thus a 33% loss in performance, a third the of total cost to replace (making it like a 6th of the costs compaired to component B)
If component B fails, 100% loss, complete downtime, 100% expense. (relatively)
It's a lot easier and cheaper to make failure-tolerant software if you're looking at system functionality on a cluster/datacentre level than it is to ensure all your hardware is bulletproof.
Hardware will fail - it's up to the intelligence of the overlaid systems to mitigate that.
You could say that Google is taking advantage of the fact that hardware is unreliable to reduce cost.
With server farms the size of Google's, failures are going to occur daily regardless of how "fault-tolerant" your hardware is. Nothing is 100% failure free. Given that failures will occur, you need fault tolerance in your software, and if your software is fault tolerant, then why waste money on overpriced "fault-tolerant" hardware? If you can buy N cheapo servers for the price of 1 hardened one, then you'll typically have N times the CPU power available, and the software makes them both look as reliable.
You're also paying through the nose for every extra nine of uptime.
That's not to say it's impossible, IBM, HP, any of the "big iron" companies can offer you damn near 100% uptime without major changes to your software.
But be prepared to pull out the checkbook. You know, the REALLY BIG one that is only suitable for writing lots of zeroes and grand prize giveaways.
And even if you think of Google as a whole, it is significantly more popular in Europe and the US than it is in Asia, so you would still have uneven traffic rates.
Full Tilt
I think mostly what they are doing, is buying 3 of something cheaper, instead of one of something greater.
From what it looks like they're doing exactly what I do for myself; skip the extraneous crap and simply rack motherboards as they are.
In that case we're not talking 3 of something cheaper; you could probably get up towards 5-10 of something cheaper. Then consider that best price/performance is not generally what is bought, and the difference is even wider.
Of course, it's not going to happen in the average corporation, where most involved parties prefer covering their ass by buying conventional branded products. Point out to your average corporate purchaser or technical director that you could reduce CPU cycle costs to 1/25 th, and that you could provide storage at 1/100th of the current per gigabyte cost and they'll whine 'but we're an _enterprise_, we cant buy consumer grade stuff or build it ourselves'.
Ten years ago people brought obsolete junk from work home to play with. These days I'm considering bringing obsolete stuff from home to work because the stuff I throw out is often better than low-prioritized things at work.
First let me state that I'm a mainframe systems programmer and a true believer of this technology. IMHO Google should start looking at mainframe based virtualization instead of the server farms they currently depend on.
One z10 complex with 64 CPU's, 1.5 TB of memory, can support thousands of Linux instances all communicating with each other using hypersocket technology. Hypersockets uses microcode to enable communications between environments without going to the actual network.
A z10 processor complex is as close to 100% fault tolerant as possible, energy efficient, cost effective when compared to the total cost of the alternatives.