Promise PDC20267 ATA RAID, poor write performance

[Søren Schmidt]

Frode Nordahl wrote:
> Hello,
> 
> I have a intel S845WD1-E board with onboard Promise PDC20267 controller.
> The system is set up with a P4 2Ghz with 1GB RAM.
> The board also has a Intel ICH2, but that's only used by a CDROM.
> 
> Disks connected:
> ad4: 39205MB <Maxtor 6E040L0/NAR61590> [79656/16/63] at ata2-master UDMA100
> ad6: 39205MB <Maxtor 6E040L0/NAR61590> [79656/16/63] at ata3-master UDMA100
> 
> I have them set up in a RAID1
> 
> I have tried this on FreeBSD 4.10-RELEASE, and 6-CURRENT (from today) 
> with similar results.
> 
> I also tried with RAID0, and that showed the same results*2, that is, 
> ca. 7MB/s write instead of 3.5MB/s.

Hmm that is "somewhat" on the low side, even with those Maxtors it 
should be better.

I'll try to reproduce here, I should have semilar or even identical HW 
in the ATA collection in the lab, give me a few days to get it setup...

-Søren