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Re: SW RAID read performance

On Thursday, 03.08.2006 at 07:30 -0400, Justin Piszcz wrote:

> >I have 2 disks in RAID 1 and I expected reading will be approx. 2x
> >faster then a single disk reading because there can be used the same
> >technique as on RAID 0. I tested it with bonnie++. Can linux SW RAID
> >1 read "in stripes" to boost the reading performance?
> From my benchmarking on my RAID1 (dual raptor RAID1) it appears it
> reads from one drive or the other.

It all depends on which disk controllers you're using and their

I have two, separate SATA disks on two different SATA controllers and
read performance in a RAID-1 configuration *is* (nearly) twice that of a
single disk, in many situations.  I think I've got the benchmark
statistics somewhere...

If "it appears it reads from one drive or the other" is the case, then
you probably have a bottleneck somewhere else.  Are these disks on the
same controller channel?


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