On 3/31/2013 12:56 PM, Mark Knecht wrote: > On Sun, Mar 31, 2013 at 10:41 AM, Stan Hoeppner <stan@xxxxxxxxxxxxxxxxx> wrote: >> On 3/31/2013 12:15 PM, Mark Knecht wrote: > <SNIP> >>> >>> Hopefully that gives you enough info to suggest a direction. >> >> These applications append small data slowly over a long period of time, >> which usually means fragmentation. Thus there's not much to optimize at >> the chunk/stripe level, other than keeping chunk size small to spread >> random reads over all platters. You currently have a 16KB chunk, IIRC, >> which is about as good as you'll get for this workload. Given your >> applications' low write throughput chunk/strip really doesn't matter. >> >> -- >> Stan >> > > OK, I cannot argue with your conclusions and will stick with 16K for now. > > Presumably if any improvement is to be made here its getting > everything onto a single partition instead of multiple RAIDs on the > same drives which then reduces the physical overhead (moving heads to > different partitions) and allows the md software to do the heavy > lifting? Your write IO rate appears to be so low that it really makes no difference. I'd guess you could run all of this from a single fast disk drive (10/15K or SSD) without skipping a beat. -- Stan -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
