[comp.unix.xenix] Xenix tar format

ked@garnet.berkeley.edu (Earl H. Kinmonth) (09/22/88)

Does anyone know how SCO Xenix modifies the tar format to cover
files that are spread over two or more floppies.  tar(F) does NOT
describe this.

Earl H. Kinmonth
History Department
University of California, Davis
Davis, California
95616 916-752-1636/0776

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daveh@marob.MASA.COM (Dave Hammond) (09/22/88)

In article <14605@agate.BERKELEY.EDU> ked@garnet.berkeley.edu (Earl H. Kinmonth) writes:
>Does anyone know how SCO Xenix modifies the tar format to cover
>files that are spread over two or more floppies.  tar(F) does NOT
>describe this.

Tar has always choked on files which are larger than the backup volume.
If there is a magical workaround for this, I wish someone would share it.

BTW, are there *any* copy/backup utilities besides `dump' which do
allow files to span volumes ?

Dave Hammond
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------------------------------------------------------------------------------

jfh@rpp386.Dallas.TX.US (The Beach Bum) (09/26/88)

In article <421@marob.MASA.COM> daveh@marob.masa.com (Dave Hammond) writes:
>Tar has always choked on files which are larger than the backup volume.
>If there is a magical workaround for this, I wish someone would share it.
>
>BTW, are there *any* copy/backup utilities besides `dump' which do
>allow files to span volumes ?

yes.  afio has been out for quite a while now, along with a tar from john
gilmore (gnu@hoptoad) which i believe handles this problem.

afio is VERY well done.  i've used it to backup a 270MB database to magtape
[ 78MB reels ] with no problems.  it is upwards compatible with cpio and
can be used to produce backwards compatible archives.  [ it also runs on
sco xenix and makes streaming tapes scream with reasonable flags ]
-- 
John F. Haugh II (jfh@rpp386.Dallas.TX.US)                   HASA, "S" Division

      "Why waste negative entropy on comments, when you could use the same
                   entropy to create bugs instead?" -- Steve Elias

jim@applix.UUCP (Jim Morton) (09/30/88)

> Tar has always choked on files which are larger than the backup volume.
> If there is a magical workaround for this, I wish someone would share it.
> 
> BTW, are there *any* copy/backup utilities besides `dump' which do
> allow files to span volumes ?
> 

Wait, what? As of Xenix 2.1, tar can span multiple volumes and split
files across them, and it works great! You can either do this using
the automatic defaults in /etc/default/tar, like:
	tar cv2 file1 file2 ... (for a DS/HD 96tpi floppy drive 0)
or by hand specifying the volume size and blocking factor, like:
	tar cvkbf 1200 20 /dev/fd096 file1 file2
the tar "e" option prevents any file from being split across a
volume. What tar won't do, and this would be my only complaint, is
if your doing a lot of small files and it hits the end of a volume
without splitting a file, when the user restores the floppies back
in, it won't prompt for a next volume - tar just completes and exits.
So you get some volumes where tar says "Insert next volume" and others
where tar just exits and the user has to type "tar xv..." all over again.

--
Jim Morton, APPLiX Inc., Westboro, MA
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      jim@applix.m2c.org

jpr@dasys1.UUCP (Jean-Pierre Radley) (10/01/88)

In article <421@marob.MASA.COM> daveh@marob.masa.com (Dave Hammond) writes:
>Tar has always choked on files which are larger than the backup volume.
>If there is a magical workaround for this, I wish someone would share it.

On all versions of Xenix issued for the Tandy 12-16-6000 series of machines,
tar was and is capable of spanning multiple floppies, both on reading from,
and writing to, an archive.
-- 

Time is nature's way of				Jean-Pierre Radley
making sure that everything			..!cmcl2!phri!dasys1!jpr
doesn't happen all at once.			CIS: 76120,1341