Disabling SCSI parity checking to dump disk on ACB4000 MFM-SCSI adapter?

[Jonas M]

Hi,

I remember I used Linux with an AdvanSys PCI adapter to successfully read a disk
connected through an ACB4000. It's been a while but I believe I had to run
an old kernel which I compiled myself with support for ACB4000. Might have
been that a patch was applied.

All I found in my archives is a copy of the dmesg from the host showing:

Linux version 2.0.38 (root at localhost.localdomain) (gcc version 2.7.2.3) #2 Wed Nov 11 20:33:21 CET 2009
[...]
scsi0 : AdvanSys SCSI 3.1E: PCI Ultra 16 CDB: IO D400/F, IRQ 12
scsi : 1 host.
scsi0 channel 0 : resetting for second half of retries.
SCSI bus is being reset for host 0 channel 0.
advansys: advansys_reset: reset request not active or waiting, completing anyway fbd018
  Vendor: ADAPTEC   Model: ACB-40XX          Rev: 1.00
  Type:   Direct-Access                      ANSI SCSI revision: 01
Detected scsi disk sda at scsi0, channel 0, id 0, lun 0
SCSI device sda: hdwr sector= 512 bytes. Sectors= 148135 [72 MB] [0.1 GB]
 sda: unknown partition table

Can try to dig around old disks some day to see if I find the patch.

Br,
Jonas

On Wed, Sep 23, 2020 at 08:51:39PM +0200, Michael Engel via cctalk wrote:
> Hi,
> 
> still working on backing up the Tektronix 440x disks. My current problem is
> that the ACB4000 SCSI-to-MFM adapter doesn´t support SCSI parity.
> 
> I finally managed to find a PCI SCSI controller (Adaptec 2940) and a Pentium
> 4 PC with PCI slots and installed OpenBSD 6.7. I disabled parity checking in
> the Adaptec BIOS config and it detects a disk at ID 0 with no name. So far,
> so good.
> 
> However, OpenBSD always seems to enable SCSI parity and complains about disk
> parity errors. I tried to disable all lines in the aic7xxx and ahc_pci
> driver source files that seem to enable parity, but nothing seems to make a
> difference. The drive/ACB4000 is not detected by OpenBSD, I get a "device
> not configured" error when accessing the disk device files (/dev/sdxc and
> /dev/rsdxc).
> 
> Do you know if is there another OS which would make it easier to change
> crucial SCSI parameters in the driver (config) or maybe a specialized tool
> that could help me to image the disk?
> 
> -- Michael