On Sun, 2007-04-01 at 14:19 +0200, Jan Engelhardt wrote:

Hello list,


normally, I'd think that combining drives into a raid1 array would give 
me at least a little improvement in read speed. In my setup however, 
this does not seem to be the case.

14:16 opteron:/var/log # hdparm -t /dev/sda
 Timing buffered disk reads:  170 MB in  3.01 seconds =  56.52 MB/sec
14:17 opteron:/var/log # hdparm -t /dev/md3
 Timing buffered disk reads:  170 MB in  3.01 seconds =  56.45 MB/sec
(and dd_rescue shows the same numbers)

The raid array was created using
# mdadm -C /dev/md3 -b internal -e 1.0 -l 1 -n 2 /dev/sd[ab]3


Jan

From section 9.5 in [FAQ]

"To check out speed and performance of your RAID systems, do NOT use
hdparm. It won't do real benchmarking of the arrays." <snip>

I might recommend bonnie++. I think I've seen accepted benchmarks here
using bonnie++.

[FAQ] http://tldp.org/HOWTO/html_single/Software-RAID-HOWTO/#s9

-- 
Henrik Holst [off-list ref]