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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.
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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.
The hardware failures I can understand, but needing to rewire the data center after it's been wired once, and the fact that half of them overheat? Those sound like problems that should be addressed in the engineering and installation phases of the datacenter.
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You can easily run a dozen large VMs on one of those with room to spare (assuming some of them have 2GB or 3GB of RAM allocated to them). If you limit it to ten per box, that's twenty VMs, and you can migrate servers between them or fail them over in case of a fault. Those DL380's (if you have dynamic power savings turned on) can average under 400 watts of power draw each - so 40 watts per server. In our environment, we've got 5 hosts running a ton of VMs, some of which don't have to fail over (layer 4-7 switch, also a VM), so we're getting closer to 25 or 30 watts per VM. We'd have the SAN array anyway for our primary data storage, so that wasn't much of an extra. We're using fewer data center network ports, and few fibre channel ports. We've actually been able to triple the number of "servers" we're running while actually bringing energy use down as we've retired more older servers and replaced them with VMs. And it's been a net increase in fault tolerance as well.
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Real Slashdotters not only fail to read TFAs, but they also completely miss any and all relevant information in other people's posts.
Therefore, someone may hook on your claim that Google is not skimping on hardware and try to argue that they, in fact, do. Your admission to having read TFA will go completely unnoticed.
And before you ask yourself how come I noticed it: I didn't.
And besides, I'm new here.
Ignore this signature. By order.
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.
It depends on how much downtime costs you. If Google is down for five seconds, no one will notice - they will just assume that their link is slow, blame their ISP, and hit refresh. If a telecom's billing system or a bank's transactional system is down for five seconds then they are likely to lose a lot of money. The only difference between doing this kind of thing in hardware and software is the fail-over time and the cost. Google take a slower fail-over time in exchange for lower costs. For them and for 99.9% of businesses, it makes perfect sense. The remaining 0.1% are the reason IBM's mainframe division is so profitable.
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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.
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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.