Messages in this thread | | | Date | Sun, 24 Jun 2007 19:52:54 +0400 | From | Michael Tokarev <> | Subject | Re: SATA RAID5 speed drop of 100 MB/s |
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Justin Piszcz wrote: > Don't forget about max_sectors_kb either (for all drives in the SW RAID5 > array) > > max_sectors_kb = 8 > $ dd if=/dev/zero of=file.out6 bs=1M count=10240 > 10737418240 bytes (11 GB) copied, 55.4848 seconds, 194 MB/s > > max_sectors_kb = 128 > 10737418240 bytes (11 GB) copied, 22.6298 seconds, 474 MB/s
Well. You're comparing something different. Yes, this thread is about linux software raid5 in the first place, but I were commenting about [NT]CQ within a single drive.
Overall, yes, the larger your reads/writes to the drive becomes, the faster its linear performance is. Yet you have to consider real workload instead of very synthetic dd test. It may be good approcsimation of a streaming video workload (when you feed a large video file over network or something like that), but even with this, you probably want to feed several files at once (different files to different clients), so single-threaded test here isn't very useful. IMHO anyway, and good for a personal computer test.
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