Tape dumping programs for Unix/Linux...

From: Raymond Moyers <rmoyers_at_nop.org>
Date: Thu May 2 16:37:30 2002

On Thursday 02 May 2002 12:18, you wrote:

> > Whats wrong with cat ?
>
> What's wrong with cat (and dd, and arguably the whole Un*x concept of
> files-as-bytestreams for that matter) is that it loses information. A
> magnetic tape is not an ordered stream of bytes, it is an ordered
> stream of files of records, and each record has a length.

 Here you are talking about a data tape with fields that make up records
 where the records are all the same size and the fields being varaible
 length inside the record but repeating in all the other records.

 But a tape like this, from the days when tapes was used as random
 access devices is not the format of a system archive tape is it ?

> So you are forced to result to multiple disk files to maintain the file
> structure.
> (which adds to your hassle because now you need to manage collections
> of files instead of a single tape),

 Like with a tarball ?

> and as you are copying the files to bytestreams you lose the record
> length information.

 Unless you are going to resurrect some old general ledger program
 why is this important ?

 Are we comparing apples with apples here ?

> This may come across as a flame of Un*x, and maybe it is, but really
> my point is that the Un*x model of files as bytestreams is not an
> appropriate model for magnetic tapes.

 And Why not ?
 just because you *can* stream a whole disk for example, to a file
 have you noticed that unix disk devices are not used that way
 in normal operations ?

 If it was me i would spool the whole raw image to disk, and work
 with it there ,, it can certainly be massaged into any format you
 like after that ...

 Raymond
Received on Thu May 02 2002 - 16:37:30 BST