tech-kern archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Re: SATA write performance problems (on HP MicroServer)

Michael van Elst wrote:

> (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).


Home | Main Index | Thread Index | Old Index