hard disk performance on Allnet 6500 (like Thecus N2100)

[Oliver Kiddle <okiddle@yahoo.co.uk>]

After installing Debian, I've found that the disc speed as reported by
hdparm has gone down. Before, I was getting:

/dev/sda:
 Timing cached reads:   424 MB in  2.00 seconds = 212.00 MB/sec
 Timing buffered disk reads:  158 MB in  3.01 seconds =  52.49 MB/sec

Whereas now I get:
 Timing cached reads:    60 MB in  2.00 seconds =  29.95 MB/sec
 Timing buffered disk reads:   60 MB in  3.07 seconds =  19.53 MB/sec

The discs are both Samsung HD501LJ
Looking at a comparison of dmesg outputs, I get the following line with
Debian:
sata_sil 0000:00:03.0: Applying R_ERR on DMA activate FIS errata fix
Is that perhaps related to this? Does anyone have an ideas on how to
improve the performance. The figures even for the Thecus firmware seem
rather poor compared to my desktop. I've checked the rc scripts in the
thecus firmware and can't see any relevant looking hdparm command. Only
the spindown is there.

Thanks

Oliver