On Jul 16, 2012, at 2:43 AM, Michael Hase wrote: > Hello list, > > did some bonnie++ benchmarks for different zpool configurations > consisting of one or two 1tb sata disks (hitachi hds721010cla332, 512 > bytes/sector, 7.2k), and got some strange results, please see > attachements for exact numbers and pool config: > > seq write factor seq read factor > MB/sec MB/sec > single 123 1 135 1 > raid0 114 1 249 2 > mirror 57 0.5 129 1 > > Each of the disks is capable of about 135 MB/sec sequential reads and > about 120 MB/sec sequential writes, iostat -En shows no defects. Disks > are 100% busy in all tests, and show normal service times.
For 7,200 rpm disks, average service times should be on the order of 10ms writes and 13ms reads. If you see averages > 20ms, then you are likely running into scheduling issues. -- richard > This is on > opensolaris 130b, rebooting with openindiana 151a live cd gives the > same results, dd tests give the same results, too. Storage controller > is an lsi 1068 using mpt driver. The pools are newly created and > empty. atime on/off doesn't make a difference. > > Is there an explanation why > > 1) in the raid0 case the write speed is more or less the same as a > single disk. > > 2) in the mirror case the write speed is cut by half, and the read > speed is the same as a single disk. I'd expect about twice the > performance for both reading and writing, maybe a bit less, but > definitely more than measured. > > For comparison I did the same tests with 2 old 2.5" 36gb sas 10k disks > maxing out at about 50-60 MB/sec on the outer tracks. > > seq write factor seq read factor > MB/sec MB/sec > single 38 1 50 1 > raid0 89 2 111 2 > mirror 36 1 92 2 > > Here we get the expected behaviour: raid0 with about double the > performance for reading and writing, mirror about the same performance > for writing, and double the speed for reading, compared to a single > disk. An old scsi system with 4x2 mirror pairs also shows these > scaling characteristics, about 450-500 MB/sec seq read and 250 MB/sec > write, each disk capable of 80 MB/sec. I don't care about absolute > numbers, just don't get why the sata system is so much slower than > expected, especially for a simple mirror. Any ideas? > > Thanks, > Michael > > -- > Michael Hase > http://edition-software.de<sata.txt><sas.txt>_______________________________________________ > zfs-discuss mailing list > firstname.lastname@example.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss -- ZFS Performance and Training richard.ell...@richardelling.com +1-760-896-4422
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