2 May
2002
2 May
'02
8:18 a.m.
Raymond Moyers <rmoyers(a)nop.org> wrote:
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. 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), and as you are copying the files
to bytestreams you lose the record length information.
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.
-Frank McConnell
At 02:01 AM
5/2/2002 -0700, Ethan Dicks wrote:
I can use dd to slurp
stuff off of tape, but it's tedious. What tools are people using for
tape archiving under Linux or Solaris? AIX seems to come with "tcopy"
that essentially pulls everything off the tape until logical or physical
EOT. I'm looking for something similar - point it at the drive and
siphon it on down.
Whats wrong with cat ? 
2 May
2 May
12:37 p.m.
On Thursday 02 May 2002 12:18, you wrote:
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 ?
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. 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
8123
days inactive
8123
days old
1 comments
2 participants
participants (2)
-
fmc＠reanimators.org -
rmoyers＠nop.org