pitiful performance of an SATA150 drive

[Søren Schmidt]

Derek Ragona wrote:
> The 500 GB drives I have seen are SATA300, backward compatible to 
> SATA150.  If your's is SATA300, you might consider replacing the 
> controller with an add-on SATA300 controller.

That would make no difference whatsoever, todays drives are not even 
close to maxing out the SATA150 interface speed.

> You didn't say what brand or model your drive is.  Different models come 
> with different sizes caches on the drives which effects performance.  
> Also depending on the drive read or write caching may or may NOT be 
> enabled.  Usually the drive manufacturer has a utility to examine and 
> set these values.

Caches are always turned on pr default in FreeBSD (if they exist), so 
nothing to get here *unless* write cache is turned of in the loader.

>> I installed a new 500Gb SATA drive into my 6.1 system and am greatly
>> disappointed with its performance. Although straight reading is
>> Ok at around 32Mb/s, the writing is never more than 7Mb/s (as reported
>> by `systat 1 -vm' while running `cat < /dev/zero > /dev/ad8').

The problem is the blocksize that gets in the way of utilizing full 
transfer speed. As I told the originator earlier in private mail one 
could use dd with a blocksize of 1Mbyte to test the actual max transfer 
speed to/from the drive.

-Søren