🚀 go-pugleaf

A. Lester Buck III (buck@trinity.tc.cornell.edu) wrote:
: In article <2rfr8p$41t@netnews.upenn.edu> kirsten@ssc.sas.upenn.edu (Kirsten Starcher) writes:
: >We have a large number of IBM mainframe 9-track tapes, both labelled
: >and unlabelled, that we would like to transcribe to our RS/6000s.  Does
: >anyone know of a script or program that we could use to make a dumb
: >copy of the tapes to online storage? (Preserving record length and
: >block size.)

: I am not following you here - "transcribe" to what?  The basic
: "otherscsi" magnetic tape driver on AIX 3.2.5 should have no trouble
: reading from a generic SCSI 9-track tape drive.  There is software
: around that does labeled tapes.  The AT&T Unix Toolchest has something,
: for example.  If you have a lot of tapes, you probably don't want to
: rewrite them all.  The EBCDIC conversion can be done on the fly.  Or
: maybe you want to convert everything into tar format?

Our problem is that we have hundreds of tapes, not all of them labelled. 
In addition, some files are in the beloved IBM RECFM U format (forcing us
to preserve block length information on our copies). Also, we are
ultimately going to have to peruse many of these tapes to determine what
to keep, and what to toss.  For a number of reasons, we intend to defer
that job to later, after they have been copied.  Right now, all we want to
do is copy the tapes to online storage (to be tar'ed or otherwise archived
later).  But it has to be done in such a way that we can recreate the
original tapes exactly.  (We don't want to do EBCDIC/ASCII translation on
a file that we wrongly assumed to be EBCDIC). 

We have decided, for the time being, to treat labelled tapes and 
unlabelled tapes identically, ... i.e. the header and trailer labels on 
the tapes will just be copied as individual files.  So what we think we'll 
need to do is this:

  for each physical file on the 9-track tape, make a file on our output
      medium of choice.

  for each block in each file
     read the block with no translation or truncation.

     measure the length of the block

     write an output record composed of the concatenation of
      - a 2 byte integer equal to the input block length plus 2
      - the untranslated input block

     (i.e. we're imitating how the IBM mainframe does variable length
      records).

Then later we can deal with data translation issues.

We were hoping somebody who reads this request might have already dealt 
with this problem.


kirsten@ssc.sas.upenn.edu