hi,

it would also be interesting to see before & after for a 64k i/o size
as well.  also, I take it your bonnie output involved a filesystem?
I'm surprised that it would be that slow, I get much better
performance than that from a filesystem.

-Chuck


On Wed, Sep 05, 2001 at 11:13:21AM -0600, Greg Oster wrote:
> In the "before" case, I was seeing:
> 
> somebox# time dd if=/dev/rsd1g of=/dev/null bs=8k count=40000
> 40000+0 records in
> 40000+0 records out
> 327680000 bytes transferred in 12 secs (27306666 bytes/sec)
> 0.0u 1.2s 0:12.03 10.3% 0+0k 0+1io 0pf+0w
> somebox# time dd if=/dev/zero of=/dev/rsd1g bs=8k count=40000
> 40000+0 records in
> 40000+0 records out
> 327680000 bytes transferred in 248 secs (1321290 bytes/sec)
> 0.0u 1.5s 4:07.92 0.6% 0+0k 0+2io 0pf+0w
> somebox# 
> 
> AFTER turning on the write-back cache performance jumped to:
> 
> somebox# dd if=/dev/zero of=/dev/rsd0g bs=8k count=40000
> 40000+0 records in
> 40000+0 records out
> 327680000 bytes transferred in 11 secs (29789090 bytes/sec)
> somebox# 
> 
> And the RAID set saw a nice boost too:
> 
>               -------Sequential Output-------- ---Sequential Input-- --Random--
>               -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
> Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
> before   1000  4311  9.4  4301  3.0  3779  3.9 24568 65.6 24194 14.7 129.3  2.5
> after    1000 15146 33.3 15183 10.8  5887  5.9 23786 63.2 23842 14.4 116.7  2.2
> 
> (RAID 1 set made up of two 9GB U160 <IBM-PSG, DDYS-T09170M  M, S9HA> drives in 
> an IBM x330 1U server box (256MB, 1GHz PIII).)
> 
> Colour me a very happy camper... :)
> 
> Later...
> 
> Greg Oster
> 
>