Glenn Cole <[log in to unmask]> wrote:

>Tom Brandt writes:
>> So it seems there is no way to validate a DDS3 backup.
>
>No reasonable way, in any case.
>
>IIRC, Alfredo used the only true technique a couple decades ago:
>he used a separate machine (with a tape drive other than the one
>used for the :STORE) to actually restore the files.

Actually, I HAVE BEEN USING the technique of physically RESTORING all the
files from a backup tape for a couple of decades (i.e., I didn't "do it" a
couple of decades ago and then quit doing it :-)

Not to imply that I am paranoid, but when I am on the road using my Gypsy
HP3000, I do a daily partial backup to a DDS tape, which I mail to Sun
Valley (and which Rene eventually restores for me on my primary machine as
well as on my secondary machine).

Not being the trusting type, I massage STORE's output listing to create an
indirect file for LZW (thanks, Randy Medd @ Telamon).  I produce an LZW
file with the affected files and download it from the HP3000 to my Mac
PowerBook.  I then upload this LZW file to my secondary HP3000 in Sun
Valley via a phone call and PPP (and I also keep the LZW file, archived by
date, on my PowerBook and on the PowerBook's backups).  Once the LZW file
reaches Sun Valley, I expand it on my secondary machine, just to make sure
that all the files are there.

Why don't I simply expand the LZW file into my primary machine?  Because
LZW changes the creation & modification dates (which I prefer to keep
"true" for historical reasons), so I prefer to RESTORE from one of the TWO
DDS tapes which I produce on my last day on the road and which I bring back
with me in addition to the one I mail to Sun Valley and arrives a few days
after my return.  Should this DDS tape fail to restore, then I would expand
the last LZW file into my primary machine.  So far, all DDS tapes have
worked just fine.

It is important to note that, after restoring files (or after expanding LZW
files) onto my secondary machine, I schedule a full suite of batch jobs
(including compile & link jobs) just to make sure that, besides simply
restoring, the files have a fighting chance of being correct.

The likelihood that ALL of these backups and verifications (implemented
using different technologies) will fail to "restore meaningfully" seems
reasonably small to me :-)


 _______________
|               |
|               |
|            r  |  Alfredo                     mailto:[log in to unmask]
|          e    |                                  http://www.adager.com
|        g      |  F. Alfredo Rego                       +1 208 726-9100
|      a        |  Manager, R & D Labs               Fax +1 208 726-2822
|    d          |  Adager Corporation
|  A            |  Sun Valley, Idaho 83353-3000                   U.S.A.
|               |
|_______________|