On Wed, Mar 30, 2011 at 12:12:14PM -0400, Joe Landman wrote: > >- T610: > > > >32000+0 enregistrements lus > >32000+0 enregistrements écrits > >1048576000 octets (1,0 GB) copiés, 0,870001 s, 1,2 GB/s > > > >- PE2900: > > > >32000+0 records in > >32000+0 records out > >1048576000 bytes (1.0 GB) copied, 9.11934 s, 115 MB/s > > Ahhh ... look at that. Cached write is very different between the > two. An order of magnitude. You could also try a direct > (noncached) write, using oflag=direct at the end of the line. This > could be useful, though direct IO isn't terribly fast on MD raids. > > If we can get the other dd's indicated, we might have a better sense > of which layer is causing the issue. It might not be MD. Hi, FWIW I removed a disk from the raid6 array, formatted a partition as xfs and mounted it to test write speed on a single device: - T610 (LSI Logic SAS2008 + 8 X WDC Caviar Black WD1002FAEX): ZENON:/mnt/test# time tar -xjf /usr/src/linux-2.6.37.tar.bz2 tar -xjf /usr/src/linux-2.6.37.tar.bz2 21.89s user 3.93s system 44% cpu 58.115 total ZENON:/mnt/test# time rm linux-2.6.37 -rf rm -i linux-2.6.37 -rf 0.07s user 2.29s system 1% cpu 2:28.32 total - PE2900 (MegaRAID SAS 1078 + 8 X Hitachi Ultrastar 7K1000): PYRRHUS:/mnt/test# time tar -xjf /usr/src/linux-2.6.37.tar.bz2 tar -xjf /usr/src/linux-2.6.37.tar.bz2 18.00s user 3.20s system 114% cpu 18.537 total PYRRHUS:/mnt/test# time rm linux-2.6.37 -rf rm -i linux-2.6.37 -rf 0.03s user 1.68s system 63% cpu 2.665 total This would mean that the problem really lies with the controller or the disks, not the raid6 array. -- 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
