Thanks guys! >> raid10: 220MB/s > > Assuming the default 'n2' layout, I would expect 2*140 or 280, so this is a > little slow. Try "--layout=f2" and see what you get (should be more like > RAID0). mdadm -C /dev/md0 --level=raid10 --layout=f2 --raid-devices=4 /dev/sda1 /dev/sdc1 /dev/sdd1 /dev/sde1 dd if=/dev/md0 of=/dev/null bs=1M count=1000 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 2.23352 s, 469 MB/s :D awesome!! > >> raid5: ~165MB/s > > I would expect 3*140 or 420, so this is very slow. I wonder if read-ahead is > set badly. > Can you: > blockdev --getra /dev/md0 > multiply the number it gives you by 8 and give it back with > blockdev --setra NUMBER /dev/md0 > genius. im not really sure what this did but it totally fixed the problem. look ahead was 768, set it 6144 and immediately got 400MB/s > >> raid1: ~140MB/s (single disk speed) > > as expected. > >> >> for 4 disks raid0 seems like suicide, but for my system drive the >> speed advantage is so great im tempted to try it anyway and try and >> use rsync to keep constant back up. > > If you have somewhere to rsync to, then you have more disks so RAID10 might > be an answer... but I suspect you cannot move disks around that freely :-) > no need now! f2 layout is awesome. many thanks, Liam > NeilBrown > > > >> >> cheers for you responses, >> >> Liam > -- 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
