On 15/09/2009 18:56, Doug Ledford wrote:
On Sep 10, 2009, at 2:44 PM, Majed B. wrote:
The maximum throughput you'll get is the PCI bus's speed. Make sure to
note which version your server has.
The silicon image controller will be your bottleneck here, but I don't
have any numbers to say how much of a loss you'll be at. You'd have to
search around for those who already benchmarked their systems, or
buy/request a card to test it out.
I've actually been doing some of those benchmarks here. Given a Silicon
Image 3124 card in a x1 PCI-e slot, my maximum throughput should be
about 250MB/s (PCI-e limitation). My drives behind the pm are all
capable of about 80MB/s, and I have 4 drives. What I've found is that
when accessing one drive by itself, I get 80MB/s. When accessing more
than one drive, I get a total of about 120MB/s, but it's divided by
however many drives I'm accessing. So, two drives is roughly 60MB/s
each, 3 drives about 40MB/s each, and 4 drives about 30MB/s each.
Were you using a SiI3124-1 (1.5Gbps, they claim 150MB/s) or SiI3124-2
(3Gbps/300MB/s)? What throughput can you get using all 4 channels of the
SiI3124 simultaneously, not using the port multiplier - does that top
out at 120MB/s too?
And have you done similar testing of your port multiplier hanging off a
motherboard SATA port? Do you get anywhere nearer the 3Gbps?
Just interested...
Cheers,
John.
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
