Good point. They mainly get that 10-20% with compression. (They use compression after they've de-duped.) They're at different levels of granularity, so it still works.
--- W. Curtis Preston Backup Blog @ www.backupcentral.com VP Data Protection, GlassHouse Technologies -----Original Message----- From: Dave Mussulman [mailto:[EMAIL PROTECTED] Sent: Friday, August 31, 2007 1:34 PM To: Curtis Preston Cc: ADSM-L@VM.MARIST.EDU Subject: Re: Data Deduplication 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. Dave
