On Thu, Oct 18, 2007 at 09:07:45PM +0000, Fab wrote: > Hello, > > Lately I tried some different configurations (lvm & partition) to divide my raid > 5 array. you might want to check out http://www.miracleas.com/BAARF/BAARF2.html talks about why you might not want to use raid5 in this config and maybe raid1/0 > > I noticed that partitioning the array was resulting in far better performances > than using lvm. > > I have the following configuration : > > ------------------------- > # mdadm --detail /dev/md0 > > /dev/md0: > Version : 00.90.03 > Creation Time : Sun Sep 23 12:29:14 2007 > Raid Level : raid5 > Array Size : 1435825152 (1369.31 GiB 1470.28 GB) > Device Size : 478608384 (456.44 GiB 490.09 GB) > Raid Devices : 4 > Total Devices : 4 > Preferred Minor : 0 > Persistence : Superblock is persistent > > Update Time : Thu Oct 18 22:42:12 2007 > State : clean > Active Devices : 4 > Working Devices : 4 > Failed Devices : 0 > Spare Devices : 0 > > Layout : left-symmetric > Chunk Size : 128K > > UUID : 0d69d64b:89ec4fb0:e4564657:5e4ed718 > Events : 0.80 > > Number Major Minor RaidDevice State > 0 8 3 0 active sync /dev/sda3 > 1 8 19 1 active sync /dev/sdb3 > 2 8 35 2 active sync /dev/sdc3 > 3 8 51 3 active sync /dev/sdd3 > ------------------------- > > > I tried a lot of different configurations when I made my logical volumes, > but none worked better. I don't know could be wrong. > > Here are my benchmarks : > > ------------------------- > # dd if=/dev/md0 of=/dev/null bs=100M count=20 > 20+0 records in > 20+0 records out > 2097152000 bytes (2.1 GB) copied, 9.58494 seconds, 219 MB/s > > dd if=/dev/raidvol1/data1 of=/dev/null bs=100M count=20 > 20+0 records in > 20+0 records out > 2097152000 bytes (2.1 GB) copied, 12.396 seconds, 169 MB/s > > # dd if=/dev/raidvol1/data2 of=/dev/null bs=100M count=20 > 20+0 records in > 20+0 records out > 2097152000 bytes (2.1 GB) copied, 13.4758 seconds, 156 MB/s > > # dd if=/dev/raidvol1/home1 of=/dev/null bs=100M count=20 > 20+0 records in > 20+0 records out > 2097152000 bytes (2.1 GB) copied, 17.7541 seconds, 118 MB/s > ------------------------- > > If I use a partitioned array, then I get the best performances (same than > /dev/md0 : about 220MB/s). With LVM, it has been impossible to get more than > 170MB/s in "any" configuration. > > I'm not quite sure why I'm getting these results. Any ideas about > what could be wrong, or what to look for? > > Thanks in advance, > > Fabien > > > -- > To UNSUBSCRIBE, email to debian-user-REQUEST@lists.debian.org > with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org > >
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