Steinar, On 1/31/06 5:26 PM, "Steinar H. Gunderson" <sgunderson@xxxxxxxxxxx> wrote: > cassarossa:~# grep md1 /proc/mdstat > md1 : active raid1 sdf6[1] sda6[0] > cassarossa:~# dd if=/dev/sda6 of=/dev/null bs=8k count=400000 > [system at about 35% wait for I/O and 15% system, according to top] > 400000+0 records in > 400000+0 records out > 3276800000 bytes transferred in 54,488154 seconds (60137842 bytes/sec) > [system at about 45% wait for I/O and 7% system -- whoa?] > 400000+0 records in > 400000+0 records out > 3276800000 bytes transferred in 52,523771 seconds (62386990 bytes/sec) > > I'm not sure if it _refutes_ the assertion that the Linux RAID-1 driver can > do balancing of sequential reads, but it certainly doesn't present very much > evidence in that direction. BTW, sda and sdf are on different channels of a > dual-channel (onboard, connected via PCI-X) Adaptec board, so I doubt the bus > is the limiting factor. Yep - 2MB/s is noise. Run a RAID0, you should get 120MB/s. Incidentally, before this thread took a turn to RAID10 vs. RAID5, the question of HW RAID adapter versus SW RAID was the focus. I routinely see numbers like 20MB/s coming from HW RAID adapters on Linux, so it's nice to see someone post a decent number using SW RAID. We're very happy with the 3Ware HW RAID adapters, but so far they're the only ones (I have two Arecas but I mistakenly ordered PCI-E so I can't test them :-( - Luke
