ADSM-L

[no subject]

1996-01-04 11:11:33
From: Terry A Moore <tmoore AT TIMKEN DOT COM>
Date: Thu, 4 Jan 1996 11:11:33 -0500
Simon Travaglia (spt AT waikato.ac DOT nz) replied:

> The problem with duplicate files is that a lot of the time they'll
> look like duplicates but will not in fact be that way.  Take for
> instance an application that is 'customised' by the installation
> process to work only on a single machine.  It has an IP number,
> Ethernet address or Name to distinguish itself.  Stashing only one
> copy of photoshop say, because they all have exactly the same file
> size, would not work.  It's possible that even checksumming might
> not work because it's conceivable that the checksum is 'padded'
> after the customisation process to match the original.

Forcing a checksum to come out the same on a modified version of the
file seems like a pretty unusual situation, but that would be the reason
for making this feature optional/configurable.

> The interim way around not backing up multiple copies of data is
> to not back it up at all.  If it's in multiple places and easily
> installable, why not exclude the entire directory, or certain file
> specs.  Another option is to have application areas and data areas
> on the client.  Never backup the application areas and always
> backup the data areas.

Unfortunately Windows applications have a way of slip-streaming updates
into the Windows directories.  You can't always go back and re-install
unless you make sure that you reinstall all the products in the "right"
sequence so that you have the proper version of a DLL for example in
WINDOWS\SYSTEM when you finish up.  Add to that the fact that these
application directories contain configuration files that have been
customized and you wind up wishing you had the ability to simply do a
restore of what was there yesterday.

Since ADSM doesn't have the "one copy" feature that we want, we are
currently excluding selected file extensions (e.g. EXE DLL) but continue
to backup others (e.g. INI) files that are likely to be unique and
perhaps customized.  If ADSM can handle my current volume and growth,
then I'd just remove this exclusion and have the disaster recovery
solution that I need.

BTW, absolutely no criticism intended here.  I'm pleased to get some
thoughts on the matter, and have found this list to be one of the best
that I subscribe to.

-----------------------------------------------------------------------
Terry A. Moore             |      "I believe OS/2 is destined to be the
Terry A. Moore             |      "I believe OS/2 is destined to be the
Sr. I/S Tech Specialist    |      most important operating system, and
The Timken Co.             |      possibly program, of all time"
tmoore AT timken DOT com          |                           Bill Gates
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