I did the final day keynote at the Conference on Innovative Data Systems Research earlier this month. The slide deck is based upon the CEMS paper: The Case for Low-Cost, Low-Power Servers but it also included a couple of techniques I’ve talked about before that I think are super useful:
· Power Load Management: The basic idea is to oversell power, the most valuable resource in a data center. Just as airlines oversell seats, there revenue producing asset. Rather than taking the data center critical power (total power less power distribution losses and mechanical loads) and then risking it down by 10 to 20% to play it safe since utility over-draw brings high cost. Servers are then provisioned to this risked down critical power level. But, the key point is that almost no data center is ever anywhere close to 100% utilized (or even close to 50% for that matter but that’s another discussion) so there is close to zero chance that all servers will draw their full load. And, with some diversity of workloads, even with some services spiking to 100%, we can often exploit the fact that peak loads across dissimilar services are not fully correlated. On this understanding, we can provision more servers than we have critical power. This idea was originally proposed by Xiabo Fan, Wolf Weber, and Luiz Barroso (all of Google) in Power Provisioning in a Warehouse-Sized Computer. It’s a great paper.
· Resource Consumption Shaping: This is an extension to the idea above of applying yield management techniques to power and instead applying to all resources in the data center. The key observation here is that nearly all resources in a data center are billed at peak. Power, Networking, Servers counts, etc. It all bills at peak. So we can play two fairly powerful tricks: 1) exploiting workload heterogeneity and over-subscribing all resources just as we did with power in Power Load Management above, and 2) move peaks to valleys to further reduce costs and exploit the fact that the resource valleys are effectively free. This is an idea that Dave Treadwell and I came up with a couple of years back and it’s written up in more detail in Resource Consumption Shaping.
The slide deck I presented at the CIDR conference are at: http://mvdirona.com/jrh/TalksAndPapers/JamesHamilton_CIDR2009.pdf.
–jrh
James Hamilton, Amazon Web Services
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