I just upgraded my SS20 to 1.5ZA, kernel built from sources updated
Dec 31.  Userland via a snapshot built a day or so before that.

# uname -a
NetBSD too.crufty.net 1.5ZA NetBSD 1.5ZA (TOO) #0: Tue Jan  1 03:00:52 PST 2002     root@too.crufty.net:/l0/sys/compile/TOO sparc

This mornings report from amanda had (same for each fs on the SS20):

/-- too        / lev 1 STRANGE
sendbackup: start [too:/ level 1]
sendbackup: info BACKUP=/sbin/dump
sendbackup: info RECOVER_CMD=/usr/bin/gzip -dc |/sbin/restore -f... -
sendbackup: info COMPRESS_SUFFIX=.gz
sendbackup: info end
|   DUMP: Found /dev/rsd0a on / in /etc/fstab
|   DUMP: Date of this level 1 dump: Wed Jan  2 04:20:40 2002
|   DUMP: Date of last level 0 dump: Tue Jan  1 04:46:49 2002
|   DUMP: Dumping /dev/rsd0a (/) to standard output
|   DUMP: Label: none
|   DUMP: mapping (Pass I) [regular files]
|   DUMP: mapping (Pass II) [directories]
|   DUMP: estimated 165602 tape blocks.
|   DUMP: Volume 1 started at: Wed Jan  2 04:20:49 2002
|   DUMP: dumping (Pass III) [directories]
|   DUMP: dumping (Pass IV) [regular files]
? Bus error - core dumped
|   DUMP: 76.25% done, finished in 0:01
|   DUMP: 165734 tape blocks
|   DUMP: Volume 1 completed at: Wed Jan  2 04:27:24 2002
|   DUMP: Volume 1 took 0:06:35
|   DUMP: Volume 1 transfer rate: 419 KB/s
|   DUMP: Date of this level 1 dump: Wed Jan  2 04:20:40 2002
|   DUMP: Date this dump completed:  Wed Jan  2 04:27:24 2002
|   DUMP: Average transfer rate: 419 KB/s
|   DUMP: level 1 dump on Wed Jan  2 04:20:40 2002
|   DUMP: DUMP IS DONE
sendbackup: size 165734
sendbackup: end
\--------

No actual core files can be found.  Any guesses as to who dumped core?

FWIW the amanda binaries were build ages ago... probably 1.5, but no
later that 1.5S