I have a DEC made Pentium II (a "DEC Server 1000") with an onboard
AIC7880 that has been acting up lately.  Every so often the following
mesage would pop up on the console:

ahc1: target 1 synchronous at 10.0MHz, offset = 0x8

I assumed that this was being caused by a flakey drive, so I swapped
that unit out (an old Seagate "Hawk") for a brand new drive made by
IBM (DDRS-34560D), now at ID 12.  Unfortunately, the new hardware
solved nothing.  

This morning, the above message was being repeatedly outputted by the
kernel (except the target in question is now 12, not 1).  I decided to
wait and see if things would get better, but the kernel kept spitting
out the message for another 2 to 3 hours!  Ultimately, the machine
paniced with the following messages:

sd0(ahc1:0:0): timed out in message in phase, SCSISIGI == 0xb6
sd1(ahc1:12:0): asserted ATN - device reset in message buffer
ahc1: target 0 synchronous at 20.00MHz, offset = 0xf  

mode = 0x100644, inum = 2114, fs = /
panic: ffs_valloc: dup alloc 

(machine drops into the kernel debugger)

Does anybody know what could be causing these panics?  Below is the
kernel message buffer output after a reboot.


Copyright (c) 1996, 1997, 1998
    The NetBSD Foundation, Inc.  All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
    The Regents of the University of California.  All rights reserved.

NetBSD 1.3.3 (NOTHING) #3: Thu Feb 25 00:42:42 EST 1999
    root@localhost:/sys/arch/i386/compile/NOTHING
cpu0: family 6 model 3 step 4
cpu0: Intel Pentium II (686-class)
real mem  = 268038144
avail mem = 262078464
using 2822 buffers containing 13504512 bytes of memory
mainbus0 (root)
pci0 at mainbus0 bus 0: configuration mode 1
pchb0 at pci0 dev 0 function 0
pchb0: Intel 82441FX PCI and Memory Controller (PMC) (rev. 0x02)
pcib0 at pci0 dev 7 function 0
pcib0: Intel 82371AB PCI-to-ISA Bridge (PIIX4) (rev. 0x01)
Intel 82371AB IDE controller (PIIX4) (IDE mass storage, interface 0x80, revision
 0x01) at pci0 dev 7 function 1 not configured
Intel 82371AB USB Host Controller (PIIX4) (USB serial bus, revision 0x01) at pci
0 dev 7 function 2 not configured
Intel 82371AB Power Management Controller (PIIX4) (miscellaneous bridge, revisio
n 0x01) at pci0 dev 7 function 3 not configured
ppb0 at pci0 dev 17 function 0: Digital Equipment DECchip 21152 PCI-PCI Bridge (
rev. 0x02)
pci1 at ppb0 bus 1
ahc0 at pci1 dev 8 function 0
ahc0: interrupting at irq 5
ahc0: aic7870 Single Channel, SCSI Id=7, 16 SCBs
scsibus0 at ahc0 channel 0: 8 targets
S3 Trio64V2/DX (VGA display, revision 0x16) at pci0 dev 18 function 0 not config
ured
ahc1 at pci0 dev 19 function 0
ahc1: interrupting at irq 10
ahc1: aic7880 Wide Channel, SCSI Id=7, 16 SCBs
scsibus1 at ahc1 channel 0: 16 targets
ahc1: target 0 synchronous at 20.0MHz, offset = 0xf
sd0 at scsibus1 targ 0 lun 0: <QUANTUM, FIREBALL SE4.3S, PJ0A> SCSI2 0/direct fi
xed
sd0: 4110MB, 7637 cyl, 4 head, 19 sec, 512 bytes/sect x 8418816 sectors
ahc1: target 5 synchronous at 10.0MHz, offset = 0x8
cd0 at scsibus1 targ 5 lun 0: <TOSHIBA, CD-ROM XM-5701TA, 0557> SCSI2 5/cdrom re
movable
ahc1: target 12 using 16Bit transfers
ahc1: target 12 synchronous at 10.0MHz, offset = 0x8
sd1 at scsibus1 targ 12 lun 0: <IBM, DDRS-34560D, DC1B> SCSI2 0/direct fixed
sd1: 4357MB, 8387 cyl, 5 head, 212 sec, 512 bytes/sect x 8925000 sectors
de0 at pci0 dev 20 function 0
de0: interrupting at irq 15
de0: DEC 21143 [10-100Mb/s] pass 3.0
de0: address 00:00:f8:7a:45:54
isa0 at pcib0
com0 at isa0 port 0x3f8-0x3ff irq 4: ns16550a, working fifo
com1 at isa0 port 0x2f8-0x2ff irq 3: ns16550a, working fifo
lpt0 at isa0 port 0x378-0x37b: polled
npx0 at isa0 port 0xf0-0xff: using exception 16
vt0 at isa0 port 0x60-0x6f irq 1
vt0: unknown s3, 80 col, color, 8 scr, mf2-kbd, [R3.32]
pms0 at vt0 irq 12
vt0: console
fdc0 at isa0 port 0x3f0-0x3f7 irq 6 drq 2
fd0 at fdc0 drive 0: 1.44MB, 80 cyl, 2 head, 18 sec
biomask 460 netmask 8460 ttymask 9462
boot device: sd0
root on sd0a dumps on sd0b
root file system type: ffs