SUMMARY: unknown dump method on tape

Date: Mon Aug 25 1997 - 14:32:30 CDT

Original question:
>Solaris 2.5
>I have received a tape with data on it dumped in an unknown way.
>Contacting the sender is impossible right now.
>I have tried:
>1) tar -tvf /dev/rmt/0
>This gives no output at all
>2) ufsrestore tvf /dev/rmt/0
>This complains that
>"Record size (512) is not a multiple of dump block size (1024)"
>3) dd if=/dev/rmt/0 of=/tmp/out
>This produces a file, but "file out" just identifies this as a "data"
>file, not compressed or tarred or anything. All I know about the
>contents is that they should be text, maybe compressed. A "strings >out"
>finds a text string in the out file, but the rest is garbage.
>How can I determine how this data was dumped to tape and are there any
>other methods for restoring data from tape besides what I have tried?
>Thank you.

The responses were:

   dd if=/dev/nrst0 of=<filename> cbs=80 conv=unblock
Did you try

4) cpio -ivt < /dev/rmt/0

Have you tried cpio?
Try tar with block size=0 , 1, 126 .
You were not really to specific on why you have this tape or what the
source was. Could it be ion ebcid format. If that is the case try using
the dd command like this:

dd if=/dev/rmt/o of=/tmp/out conv=ascii

hope it works for you!!

it might be something proprietary. maybe apollo's "rbak/wbak" tape? :)

It would be helpful if you shared that text string with the rest of us.

I'd recommend doing an "dd if=/dev/rmt/0 bs=20b| od -c" and looking at
the magic number to see if it's compressed with any of the common Unix
file compression programs (compress, gzip). You could also pipe it to
uncompress or gunzip to see if they work on it; they're picky enough
that they'll only work if they should.

If you have reason to believe that it's a dump tape, then try using
ufsrestore with different block sizes (like the 1024 suggested
by ufsrestore above).

     Another thing to try would be cpio.
You may whant to try:

tar -tvf /dev/rmt/8
tar -tvf /dev/rmt/16

It is the same device, just compressed storage.

You also have the cpio command.

cpio is at least one other method.

Its interesting that tar gave no output at all.... gtar (gnu tar) may
more info. Try messing with tar's block size....


The answer was that it was dumped with ArcServe(sp?). Thanks to all
these wonderful people who offered their advice: (Roland Grefer)
"Rodney C. Marable" <>
bismark@alta.Jpl.Nasa.Gov (Bismark Espinoza)
"Jay A. Cohen" <>
Nickolai Zeldovich <>
Rich Kulawiec <> (Magnus Hammarstrom ST/TAA)
David Robson <>

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