[Info-vax] Exabyte tapes to disk

[glen herrmannsfeldt]

Bob Koehler <koehler at eisner.nospam.encompasserve.org> wrote:
< In article <h79geb$5hf$1 at naig.caltech.edu>, glen herrmannsfeldt <gah at ugcs.caltech.edu> writes:
(snip, I wrote)
 
<> Not completely true for unix in the case of tapes, but
<> it is for disk.
 
<   As in all things eunichs, it depends on which one.  BSD UNIX dd knows
<   about blocks and records on tapes, System V knows about blocks, but
<   not records.

Well, then just grab the source for BSD dd and compile it.

But more important, the OS supplies blocking information off
the tape.  A read() call to the tape device will read one block,
or less if the block is too long (discarding the rest).  At least
BSD style do that, I believe that is true of others.

You can, then, write a program that will read tapes and write
a block-preserving disk file.  There are a few standard forms for
such files.

<   So if you have an ASCII data file on tape in 80 byte records and you
<   use BSD dd you can get it converted on the fly to stream-LF text
<   that just happens to have 80 bytes on each line.  Or you can convert
<   stream-LF text files to blank padded records as long as the longest
<   line of text, but if you live on a System V, you get to roll your own.

I haven't tried that one, but with conv=ascii it will convert FB80
EBCDIC input to LF terminated ASCII stream.

-- glen