hard drive performance

[Bruce Cran]

On Wed, 15 Apr 2009 13:54:13 +0200 (CEST)
Alexander Best <alexbestms at math.uni-muenster.de> wrote:

> hi there,
> 
> i have 2 hard drives running. the first one is SATA300 and the other
> one UDMA100. here are the dmesg entries:
> 
> ad0: 238474MB <SAMSUNG SP2504C VT100-50> at ata0-master SATA300
> ad1: 157066MB <Hitachi HDS722516VLAT80 V34OA63A> at ata4-master
> UDMA100
> 
> i've tried to test the drives' performances using the following
> commands:
> 
> dd if=/dev/ad0 of=/dev/null bs=1m count=300
> and
> dd if=/dev/ad1 of=/dev/null bs=1m count=300
> 
> the results are:
> ad0 = 314572800 bytes transferred in 4.325645 secs (72722751
> bytes/sec) ad1 = 314572800 bytes transferred in 5.166126 secs
> (60891430 bytes/sec)
> 
> the results for ad0 are a bit disappointing though. is this normal or
> is bs=1m wrong?

70MB/s is a very good transfer rate for a hard drive. The 300MB/s rate
refers to the maximum the physical interface can support, but drives
never get close to that because they can't read from disk at that
speed.

-- 
Bruce Cran