On 2/3/2012 4:10 PM, Brian Candler wrote: > On Fri, Feb 03, 2012 at 01:42:54PM -0600, Stan Hoeppner wrote: >> You've hit the peak read rate of these Hitachi drives. As others >> pointed out, if you need more read performance than the dozen of these >> you plan to RAID stripe, then you'll need to swap them for units with a >> faster spindle: >> >> 7.2k 1.21x >> 10k 1.68x >> 15k 2.53x >> >> or with SSDs, which will yield an order of magnitude increase. Your >> stated need is 20M 500-800KB files, or 20GB if my math is correct. > > Thanks for your suggestion, but unfortunately your maths isn't correct: 20M > x 0.65MB = 13TB. And that's just one of many possible datasets like this. Wow, you're right. How did I miss so many zeros? Got in hurry I guess. > I'm aware that I'm working with low-performance drives. This is intentional: > we need low power consumption so we can get lots in a rack, and large > capacity at low cost. SSDs would fulfill criteria 1/2 but obviously not 3/4. > Fortunately our workload will also parallelise easily, and throwing it > across 24 spindles will be fine. But obviously I want to squeeze the most > performance out of each spindle we have first. I'm very happy to have found > the bottleneck that was troubling me :-) Will you be using mdraid or hardware RAID across those 24 spindles? -- Stan _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
