Re: performance of san-disk

From: Willeat, Todd (TWilleat@MHP.SMHS.COM)
Date: Tue Nov 12 2002 - 17:51:46 EST


I've been able to get >70MB/s between a B80 (w/2 CPUs and 2 6228s) and a HDS
9200.

-----Original Message-----
From: Holger.VanKoll@SWISSCOM.COM [mailto:Holger.VanKoll@SWISSCOM.COM]
Sent: Tuesday, November 12, 2002 3:05 PM
To: aix-l@Princeton.EDU
Subject: performance of san-disk

Hello,

I got a p670 connected to HDS (Hitachi; 9900) Storage with 2 FC-adapter.

No matter how much disks I access concurrently, I get 34mbyte/sec maximum.
All 4 CPU are 0% idle when measuring, but depending on the # disks they
spend more time in kernel than in wait.

# disks accessed kernel wait disk-busy (topas) transfer
Mbyte/sec
10-20 8 90 50-70% 25
30 40 60 40-60% 33
40 55 45 60-80% 33
50 70 30 40-60% 34
60 78 22 35-50% 34

This looks like my CPU-power is the bottleneck, correct?

As I get 184 Mbyte/sec with the 4 internal disks and 60% kernel / 40% wait
that looks to me as if the fibre-channel driver (kernel-time) uses all my
cpu. Is this correct?

If someone likes to do some measurement to have numbers to compare, here is
the script I used:

#!/bin/sh
#dlmfdrv4 - 61
count=2000
bsk=256k
dev=dlmfdrv
#dev=hdisk

start=4
end=54

i=$start
until false
do
dd </dev/$dev$i >/dev/null bs=$bsk count=$count 2>/dev/null &
[ $i = $end ] && break
let i=i+1
done

I would appreciate any other "benchmark"-results, especially latest
ssa-technology and non hds (f.e. ibm) storage servers.

Regards,

Holger



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