Unusual RAID50 / RAID5 performance with md
Not sure if this is going to turn out to be a hardware or a software issue, but since my config is the same for both raids here goes...
I have a 6 disk RAID50 set up from 2 x 3 disk RAID5's. Basically it looks like this:
However sometimes I don't think it's as fast as it sounds. The Drives are 160GB SATA each.
I did a hdparm -t on /dev/md0, /dev/md1 and /dev/md2. Confusingly I get the following numbers:
md0: 108 MB/s
md1: 80 MB/s
md2: 66 MB/s
md2 should be the fast one, as it is the 6 disk raid50, the other two are only "sub-raids" of this. I thought they would be slower? Does anyone have an opinion on this? And most strangely of all - why would md0 be so much faster than md1? They are both software raid 5! The numbers are repeatable.