Veritas-bu

Re: [Veritas-bu] NBU7 / De-Dupe?

2010-04-02 10:48:55
Subject: Re: [Veritas-bu] NBU7 / De-Dupe?
From: "Mike Andres" <Mike_Andres AT symantec DOT com>
To: "Ed Wilts" <ewilts AT ewilts DOT org>, "David Stanaway" <david AT stanaway DOT net>
Date: Fri, 2 Apr 2010 07:48:43 -0700

Another thing to note as with many of these types of devices (VTL’s, intelligent disk, dedup applications, etc.) using OS specific tools such as df to determine used space will not give accurate numbers.  You’ll want to measure used space from the tools provided in the application or device.  There are many things to consider such as expired images that have not been cleaned up, housekeeping and garbage collection processes that return occupied blocks to the free pool, etc.  The base OS is never aware of these types of things. 

 

From: veritas-bu-bounces AT mailman.eng.auburn DOT edu [mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of Ed Wilts
Sent: Friday, April 02, 2010 9:41 AM
To: David Stanaway
Cc: veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] NBU7 / De-Dupe?

 

On Fri, Apr 2, 2010 at 8:29 AM, David Stanaway <david AT stanaway DOT net> wrote:


These number aren't that hot compared to DataDomain from my use of it.

We are seeing 86TB of backup images occupying 4.4TB of phys disk.


It all depends on the data streams and how many generations you keep.  If you keep a year's worth of weekly full copies of the same data, you're going to have 52:1 de-dupe.  If you need to only keep 1 copy and the data doesn't have duplicate blocks (e.g. TIFF images), you're going to have no de-dupe at all.

This is all VERY customer-specific.  The only way to know if a de-dupe appliance (or the software) is worth the price is to evaluate it.  You may even find, like we did, that it's suitable and justifiable for some of your data but not others.

   .../Ed

Ed Wilts, RHCE, BCFP, BCSD, SCSP, SCSE
ewilts AT ewilts DOT org

 

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