On Mon, Jul 31, 2000 at 01:43:49PM +1000, Neil Brown wrote:
> raid0 will only get close to 'n' times a single disc when you have a
> number of separate threads accessing the device, otherwise there are
> fewer opportunities for multiple drives to be accessed at once.
> I believe that bonnie is single-threaded, so it is unlikely to drive a
> raid0 array optimally.
Here are the numbers of tiobench 0.3.1 (sorry, raid0 is gone now, the
machine is in active use now)
File Block Num Seq Read Rand Read Seq Write Rand Write
Dir Size Size Thr Rate (CPU%) Rate (CPU%) Rate (CPU%) Rate (CPU%)
------- ------ ------- --- ----------- ----------- ----------- -----------
fujitsu 500 32768 1 20.07 10.1% 3.286 1.65% 17.33 15.2% 2.900 2.20%
fujitsu 500 32768 2 11.57 5.72% 3.281 1.60% 16.75 15.7% 2.960 2.26%
fujitsu 500 32768 4 10.07 5.16% 3.251 1.58% 15.15 14.2% 3.032 2.36%
fujitsu 500 32768 8 9.534 5.08% 3.269 1.56% 14.50 13.7% 3.047 2.54%
raid5-6 500 32768 1 20.55 15.1% 5.165 4.33% 2.712 4.22% 4.129 4.88%
raid5-6 500 32768 2 20.96 15.5% 6.231 5.10% 2.690 4.18% 4.069 4.89%
raid5-6 500 32768 4 21.09 15.9% 7.269 5.93% 2.693 4.21% 4.112 5.05%
raid5-6 500 32768 8 19.59 15.4% 8.145 6.89% 2.654 4.19% 4.122 5.47%
Fujitsu is a single disk, raid5-6 is the raid5 array of 6 IBM disks.
Interestingly, the read rate doesn't increase with raid5 over a single disk,
but isn't decreasing significantly either when the number of threads rise.
Sequential write is extremly disappointing.
Nils
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