Can one do disk-to-disk copys with Sun hard disks?

Can one do disk-to-disk copys with Sun hard disks?

Post by Don Nichols (Do » Sun, 22 Dec 1991 08:32:37

Quote:>>I for one don't believe in using non-standard utilities for system
>>backups.  If doing a full restore, it's unlikely you'll have these
>>special things around

>Huh?  Under normal usage, pdtar/gnutar produces archives compatible with
>traditional tar.

>>but will probably only have what's on your boot tape.

>Which probably includes tar.

        Well, he's right about that warning, since while gnutar records ALL
the modes bits, and restores them if given the proper command-line option
and run by root, the stock tar will NOT restore the modes on special files.

        I had in mind doing a partial rebuild from the distribution tapes,
loading gnutar either from a backup tape or from another system via net, and
then doing a full restore on top of the partial restore, selecting the
necessary options to gnutar to restore all mode bits and to overwrite
existing files.  It would be possible to rebuild the boot tape to include
gnutar, at least in the SunOs 3.5, but I believe that the later versions use
a different way of building the distribution tapes which makes it more
difficult.  Obviously, the latest distributions on cd-rom are beyond
modifications until we get scsi-interfaced drives capable of writing new

        Also, it is worthwhile keeping copies of gnu-tar on multiple
partitions, and, if possible, on multiple physical disks.  This increases
the chances that it'll be available when it comes time to restore from tapes.

        Merry Xmas

Donald Nichols (DoN.)     | Voice (Days): (703) 664-1585 (Eves): (703) 938-4564

        --- Black Holes are where God is dividing by zero ---


Can one do disk-to-disk copys with Sun hard disks?

Post by peter da sil » Fri, 20 Dec 1991 08:29:27

Quote:>   This is a quick and often nice way to do this sort of copy, and I've done
> it quite a few times. Only one thing to be aware of (at least on wren disks,
> which is what we've done this on mainly) is that this copy also copies over
> the defect list.

If the defect list is at the end, or in an otherwise static place, you can
use a couple of dd's with appropriate seeks, counts, and skips to miss it.
Of course, System V/386 put the defect list at the beginning, and varies
in size... sigh. On our Xenix disks it's at the end and we do this operation

        dd if=//sys1/dev/w2 of=/dev/w3 bs=1k count=323424

We also have a "dd" workalike that does retries on bad blocks (and fills
them with zeroes if all else fails) that helps when things are REALLY bad.
-- Peter da Silva
-- Ferranti International Controls Corporation
-- Sugar Land, TX  77487-5012;  +1 713 274 5180
-- "Have you hugged your wolf today?"


1. Can one do disk-to-disk copys with Sun hard disks?

A lot of people, as do I, use dump piped to restore.  Here is the exact
command I use from the host to which you are copying.  NOTE it has never
failed and I have copied from lots of different disks to lots of other
different disks:

  # rsh <suninstalled host> dump 0bf 1024 - <partition> | restore xvbf 1024 -

  where <suninstall host> == host you ran suninstall on,
    and       <partition> == partition you are copying (like /dec/rsd0{a,g,h})

This has the advantage over using ``dd'' that the two disk drives don't have
to be the same type nor do they have to be partitioned the same.  And you don't
have to go back and use format to relabel the disk you copied to (as on person
identified is necessary when using the ``dd'' method).

In fact, I could write a cute script called ``fscp'' or somesuch that would
take two arguments like ``fscp fromhost:/frompath tohost:/topath'' and does
all the other stuff for you (FYI, fscp <==> filesystem cp).


National Institute of Standards and Technology / U.S. Department of Commerce

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