Malcolm Baldridge wrote: >>I'm using 4 Seagate SX118273LC (18G) drives in a software RAID-1, mostly >>because I wanted to see what putting together a RAID was like (and at >>the time I bought them, the drives were relatively cheap). >> >> > >Bad bad bad bad bad bad bad bad. RAID1 is good for fault tolerance, and >for read performance... but worse than a single drive's performance for >randomised writes. Software RAID implementations would give you worse >performance on writes under all conditions, I wager. > > Wow, an 8 bad mistake! Actually, I always kinda wondered about that. This could actually explain a lot of my latencytest results: diskread latency performance was fine, but diskwrite and diskcopy was crummy. Ok, so I dug up an ancient 0.5G Conner IDE drive I had lying around and kludged it in. Clocks in at a paltry 2MB/s transfer rate with hdparm. I was able to record 8 channels with Ardour with JACK set at 128 periods with no xrun in sight - yeehaa! I was about to plan on picking up an IDE/ATA drive tomorrow, but now I have something else to try first. Thanks, Malcolm. Joel >Try a non-RAID volume in your tests. Keep in mind that one write is >triggering TWO writes in TWO transactions over the same SCSI card (and bus, >probably). This isn't going to be good for latency or bus utilisation. > >Before you rip out too much hardware (and hair), try it with a "simple" >volume first. > >=MB= > > >
