Re: RAID-5 streaming read performance

On Wednesday July 13, jdc@uwo.ca wrote:

Here's a question for people running software raid-5:  do you get
significantly better read speed from a raid-5 device than from it's
component partitions/hard drives, using the simple dd test I did?

SCSI-160 bus, using just 4 of the 15000rpm drives:

each drive by itself delivers about 67M/s
Three drives in parallel deliver 40M/s each, total of 120M/s
4 give 30M/s each or a total of 120M/s

raid5 over 4 drives delivers 132M/s

(We've just ordered a SCSI-320 card to make better use of the drives).

So with top-quality (and price) hardware, it seems to do the right
thing.

NeilBrown