Re: SATA write performance problems (on HP MicroServer)

[Simon Burge <simonb%NetBSD.org@localhost>]

Michael van Elst wrote:

> ef%math.uni-bonn.de@localhost (Edgar =?iso-8859-1?B?RnXf?=) writes:
> 
> >I have performance problems writing to the SATA discs on my HP MicroServer.
> >In the BIOS, IDE is switched to AHCI. The discs do NOT have 4k sectors.
> >I can read more than 70MB/s.
> 
> >I can write 110 to 120 transfers per second regardless of block size.
> >With 64k blocks, that's 6.7MB/s. If I use 32k blocks, it's 3.6MB/s, on 16k 
> >blocks 1.9MB/s and so on.
> >I ruled out alignment problems by moving the test partition, one block at a 
> >time, seven times. No difference.
> 
> 
> Does your drive have write-caching disabled? You can enable it with
> 'dkctl wd0 setcache rw'.

Spot on!  The HP N40L BIOS by default disables write caching.  There's
a BIOS setting somewhere where you can enable write caching instead of
needed dkctl on each boot (which was going to be my first plan of attack
to fix this).

Cheers,
Simon.