Re: [ADSM-L] Data Deduplication

2007-08-31 16:35:59
Subject: Re: [ADSM-L] Data Deduplication
From: Dave Mussulman <mussulma AT UIUC DOT EDU>
Date: Fri, 31 Aug 2007 15:33:56 -0500
On Thu, Aug 30, 2007 at 03:09:09AM -0400, Curtis Preston wrote:
> Unlike a de-dupe VTL that can be used with TSM, de-dupe backup software
> would replace TSM (or NBU, NW, etc) where it's used.  De-dupe backup
> software takes TSM's progressive incremental much farther, only backing
> up new blocks/fragements/pieces of data that have never been seen by the
> backup server.  This makes de-dupe backup software really great at
> backing up remote offices.

We had Avamar out a few years ago pitching their solution, and we liked
everything about it except the price.  (And now that they're a part of
EMC, I don't expect that price to drop much... *smirk*)  But since we're
talking about software, there's an aspect of de-dupe that I don't think
has been explicitly mentioned yet.  Avamar said their software got
10-20% reduction on a backup of a stock Windows XP installation.  A
single system, say it's the first one you added to your backup group.
That's not two users with the same email attachments saved, or identical
files across two systems - that's hashing files in the OS (I presume
from headers in DLLs and such.)  So if you backup two identical stock XP
installs, you get 20% reduction on the first one and 100% on the second
and beyond.  Scale that up to hundreds of systems, and that's an
incredible cost savings.  Suddenly backing up entire systems doesn't
seem so inefficient anymore.


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