I've upgraded my home system from a 486 DX2/80 to an AMD K2/350 and boy
does NetBSD run nicely now!

I also changed SCSI controllers from an Adaptec 2842 to a 2940UW.
I get the following messages (as well as not seeing 1 drive):

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Dec  4 19:02:35 netman2 /netbsd: ahc1 at pci0 dev 10 function 0
Dec  4 19:02:35 netman2 /netbsd: ahc1: interrupting at irq 11
Dec  4 19:02:35 netman2 /netbsd: ahc1: aic7880 Wide Channel, SCSI Id=7, 16 SCBs
Dec  4 19:02:35 netman2 /netbsd: scsibus0 at ahc1 channel 0: 16 targets
Dec  4 19:02:36 netman2 /netbsd: ahc1: board is not responding
Dec  4 19:02:36 netman2 /netbsd: cmd fail
Dec  4 19:02:36 netman2 /netbsd: probe(ahc1:0:0): timed out in dataout phase, SCSISIGI == 0x0
Dec  4 19:02:36 netman2 /netbsd: ahc1: Issued Channel A Bus Reset #2. 1 SCBs aborted
Dec  4 19:02:36 netman2 /netbsd: ahc1: board is not responding
Dec  4 19:02:36 netman2 /netbsd: cmd fail
Dec  4 19:02:36 netman2 /netbsd: probe(ahc1:0:0): timed out in dataout phase, SCSISIGI == 0x0
Dec  4 19:02:36 netman2 /netbsd: ahc1: Issued Channel A Bus Reset #2. 1 SCBs aborted
Dec  4 19:02:36 netman2 /netbsd: ahc1: board is not responding
Dec  4 19:02:36 netman2 /netbsd: cmd fail
Dec  4 19:02:36 netman2 /netbsd: probe(ahc1:0:0): timed out in dataout phase, SCSISIGI == 0x0
Dec  4 19:02:36 netman2 /netbsd: ahc1: Issued Channel A Bus Reset #2. 1 SCBs aborted
Dec  4 19:02:36 netman2 /netbsd: ahc1: board is not responding
Dec  4 19:02:36 netman2 /netbsd: cmd fail
Dec  4 19:02:36 netman2 /netbsd: probe(ahc1:0:0): timed out in dataout phase, SCSISIGI == 0x0
Dec  4 19:02:36 netman2 /netbsd: ahc1: Issued Channel A Bus Reset #2. 1 SCBs aborted
Dec  4 19:02:36 netman2 /netbsd: ahc1: board is not responding
Dec  4 19:02:36 netman2 /netbsd: cmd fail
Dec  4 19:02:36 netman2 /netbsd: probe(ahc1:0:0): timed out in dataout phase, SCSISIGI == 0x0
Dec  4 19:02:36 netman2 /netbsd: ahc1: Issued Channel A Bus Reset #2. 1 SCBs aborted
Dec  4 19:02:36 netman2 /netbsd: ahc1: board is not responding
Dec  4 19:02:36 netman2 /netbsd: cmd fail
Dec  4 19:02:36 netman2 /netbsd: probe(ahc1:0:0): timed out in dataout phase, SCSISIGI == 0x0
Dec  4 19:02:36 netman2 /netbsd: ahc1: Issued Channel A Bus Reset #2. 1 SCBs aborted
Dec  4 19:02:36 netman2 /netbsd: ahc1: target 3 synchronous at 10.0MHz, offset = 0xf
Dec  4 19:02:37 netman2 /netbsd: sd0 at scsibus0 targ 3 lun 0: <iomega, jaz 1GB, G.60> SCSI2 0/direct removable
Dec  4 19:02:37 netman2 /netbsd: sd0: 1021MB, 1021 cyl, 64 head, 32 sec, 512 bytes/sect x 2091050 sectors
Dec  4 19:02:37 netman2 /netbsd: cd0 at scsibus0 targ 4 lun 0: <Chinon, CD-ROM CDS-525, V11> SCSI2 5/cdrom removable

================================

Is this more likely a termination issue, or that the unrecognized drive
is too old and slow? I'm using the same SCSI cable. This is what was
seen before the upgrade:

================================

Dec  3 21:07:57 netman2 /netbsd: ahc0 at isa0 port 0x1c00-0x1cff irq 11: Adaptec AHA-284x SCSI (BIOS enabled)
Dec  3 21:07:57 netman2 /netbsd: ahc0: aic7770 <= Rev C, Single Channel, SCSI Id=7, 4 SCBs
Dec  3 21:07:57 netman2 /netbsd: scsibus0 at ahc0 channel 0: 8 targets
Dec  3 21:07:57 netman2 /netbsd: ahc0: target 0 synchronous at 10.0MHz, offset = 0x8
Dec  3 21:07:57 netman2 /netbsd: sd0 at scsibus0 targ 0 lun 0: <QUANTUM, LPS540S, 590S> SCSI2 0/direct fixed
Dec  3 21:07:57 netman2 /netbsd: sd0: 516MB, 2740 cyl, 4 head, 96 sec, 512 bytes/sect x 1057616 sectors
Dec  3 21:07:57 netman2 /netbsd: ahc0: target 3 synchronous at 10.0MHz, offset = 0xf
Dec  3 21:07:57 netman2 /netbsd: sd1 at scsibus0 targ 3 lun 0: <iomega, jaz 1GB, G.60> SCSI2 0/direct removable
Dec  3 21:07:57 netman2 /netbsd: sd1: 1021MB, 1021 cyl, 64 head, 32 sec, 512 bytes/sect x 2091050 sectors
Dec  3 21:07:58 netman2 /netbsd: cd0 at scsibus0 targ 4 lun 0: <Chinon, CD-ROM CDS-525, V11> SCSI2 5/cdrom removable

++++++++++++++++++++++++++++
Marvin the Paranoid Android.