Jan Engelhardt wrote:
> 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 problem is that raid1 one doesn't do striped reads, but rather uses 
read-balancing per proc.  Try your test with parallel reads; it should be 
faster.

You could use raid10, but then you loose single-disk-image compatibility.


Thanks!

--
Al
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