ADSM-L

Re: [ADSM-L] Data Domain - questions from a meeting with DD

2009-06-24 20:17:24
Subject: Re: [ADSM-L] Data Domain - questions from a meeting with DD
From: "W. Curtis Preston" <wcplists1 AT GMAIL DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Wed, 24 Jun 2009 17:16:16 -0700
Loon, EJ van - SPLXM said:
>The Dutch guys also confirmed that compressed data is dedupable, but it
>depends how compression is done.

I agree with the last part, but it also depends on the file.  If what you're
talking about is multiple versions of the SAME compressed file over time, DD
(and other dedupe products) might not find the similarities between those
versions.  This is because when the middle of the file changes, compressing
it again (with most compression technologies) causes the file to get
"scrambled" to the point that the patterns are not as identifiable.

The only way you're going to know for sure is to test it, but generally
speaking, I recommend against compressing before deduping.