When trying to backup to a DLT drive on a RedHat Linux 6.2 machine (x86),
from a Solaris (7) 
machine using ufsdump, I get the following error:

$ ufsdump -0uf admin2:/dev/nst0 /
  DUMP: Writing 32 Kilobyte records
  DUMP: Date of this level 0 dump: Wed Oct 18 17:43:38 2000
  DUMP: Date of last level 0 dump: the epoch
  DUMP: Dumping /dev/rdsk/c0t0d0s0 (web-1:/) to admin2:/dev/nst0.
  DUMP: Mapping (Pass I) [regular files]
  DUMP: Mapping (Pass II) [directories]
  DUMP: Estimated 3934176 blocks (1920.98MB).
  DUMP: rmtstatus: expected response size 24, got 28
  DUMP: This means the remote rmt daemon is not compatible.
  DUMP: Lost connection to remote host.
  DUMP: Bad return code from dump: 1

To me, this points to a compatability problem between Solaris and Linux
(for rmt). FWIW, there 
was a bug logged in FreeBSD, with the same problem. See:
http://www.FreeBSD.org/cgi/getmsg.cgi?fetch=108594+116864+/usr/local/www/db/text+/2000/freebsd-hackers/20000220.freebsd-hackers

(Solaris is obviously a pretty major player, and not being able to backup
from Solaris to Linux 
is a bit of a downer).

P.S. There doesn't seem to be an "rmt" package mentioned in this bugzilla,
so I had to specify it as the "dump" component :(