rdump/restore questions

[johnston at LBL-CSAM.ARPA]

We recently got an Integrated Solutions 68K box running 4.2, and now
have the problem of backing up the disks. We are connected, via an
ether, to a 780. I tried to use rdump, using the tape drive on the 780,
to do the backup.

The transfer to tape didn't go too badly, the 36 megabyte file system I
was doing went over in about 20 min (~250Kb/sec). Then, since I have
never used dump before and because I don't trust tape, I deleted a
little file and tried to restore it.  It seems that my mistrust was
well placed (or I screwed up).

I used the interactive mode in restore, and the first time it said
"badchecksum nnnnnnnnn, inode mmmmmmm" and quit. Then I listed (restore
t) the tape directory, OK; then I tried the interactive mode again.
This time the directory loaded OK, and I selected the test file I was
trying to replace. When I requested the extract of that file I got
hundreds of "resync restore, skipped nn blocks" messages, and after
about 10 min it said "change owner name in . ?". To this I answered NO,
since it should not have had to change anything to restore the file,
and restore quit. If it extracted the file I requested, I don't know
where it put it, I could not find it.

Could anyone with experience comment? Was I doing something wrong; is
this typical with dump/restore; maybe the tape was bad (it was new); or
is there something that I have overlooked?
(the command line (from memory) was:
	rdump 0fud csam:/dev/mt16 6250 /dev/el0g )

		Thanks, Bill [johnston at lbl-csam]

(P.S. The Integrated Solutions system is a real pleasure. We have
essentially the first release of their system, and we have seen no
problem worthy of the name. We use the I.S. in conjunction with an
Imagen 8/300 as a graphics/typesetter facility, and my general
impression is the the combination is 2-3 times as fast as a moderately
loaded 11/780, 4.2 system outputting the same typeset page on a
Versatec, V-80. This is not real surprising considering how much work
is done in the Imagen controller that does not have to be done in the
I.S. cpu, but it is gratifying to see, none the less.)