Reading an unknown DAT Tape

Jerry McAllister jerrymc at msu.edu
Thu Mar 15 21:07:09 UTC 2012


On Thu, Mar 15, 2012 at 03:17:05PM -0500, Martin McCormick wrote:

> 	This is a case of idle curiosity and not an urgent need
> to recover a valuable backup. I found an old DAT tape and
> attempted to read it on the very drive that probably once wrote
> it and it appears to read the tape properly in that I can use dd
> to copy it to a file and mt fsf 5, for example, takes the tape
> to the fifth file marker so there is sanity.
> 
> 	Tar, however, does not recognize the format of the
> archive so it is either something proprietary or I am not using
> the correct utility on it.
> 
> 	I opened it with dd files=2 if=/dev/sa0 of=testfile and
> then did the strings utility on testfile and got:
> 
> TAPE
> SSET
> VOLB
> DIRB
> NACL
> Setting security
> iles
> SPAD
> DIRB
> NACL
> Setting security on system files...
> SPAD
> DIRB
> NACL
> SPAD
> DIRB
> NACL
> SPAD
> FILE
> NACL
> STAN
> Jun 23 2003 12:00AM
> Jan 1 1900  8:45AM
> Jan 1 1900  9:00AM

I wondered about it being a dump(8) file, but just tried one and
strings output looked a little different.

How about a db of some sort or a log from some lab test?

////jerry



> 
> 	Note that we are obviously able to read data from the
> tape as the top few lines are readible as words. The time stamps
> at the bottom are possibly not time stamps as some of them are
> not plausible.
> 
> 	The dd command never faltered with errors although I
> did finally stop it manually.
> 
> 	Is there any FreeBSD utility that can tell more about
> what created the original archive?
> 
> 	Thank you.
> 
> Martin McCormick
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