ATA burner problem under 2.6

when using kernel 2.6.5 the following command on any DVD:

dd if=/dev/hdc of=test.iso bs=2048

uses almost 6 times as much system time compared to:

dd if=/dev/sr0 of=test.iso bs=2048 under 2.4.21 (ide-scsi, identical hardware)

Moreover: when repeating the 2.6.5 dd command a couple of times the system comes to a complete lockup, with no logged error messages whatsoever. This never happens under 2.4.21. But I can reproduce this behaviour on another PC.

Another related problem:

When ripping an audio CD under 2.4.21 I get perfect results using cdrdao with --paranioa-mode 0. Ripping the same CD under 2.6.5 requires --paranioa-mode 3.

Is this a known bug of 2.6 kernels?

Regards,

Frank-Michael Fischer