ahd0 dumps when an ext. raid attached

[Rong-en Fan]

We have an ahd0 on IBM x236 server:

ahd0: <Adaptec 29320LP Ultra320 SCSI adapter> port
0x4000-0x40ff,0x4100-0x41ff mem 0xcfffe000-0xcfffffff irq 25 at device
12.0 on pci3
ahd0: [GIANT-LOCKED]
aic7901A: Ultra320 Wide Channel A, SCSI Id=7, PCI-X 67-100Mhz, 512 SCBs

The server runs i386 6.2-RELEASE. There is a tape driver on this card. When
I attach an external RAID (U160, scsi chip is LSI1020, I think), ahd0
gets unhappy.
It dumps when the kernel tries to probe the device.

The verbose boot log is at

http://www.rafan.org/tmp/ahd0.dump.txt

This RAID works fine if I attach it to a LSI card. But due to other
reasons, I can
not use LSI card on this server.

Suggestions are welcome.

Regards,
Rong-En Fan