I think one of de-duplication's benefits is that even if 2% of your file data 
changes it doesn't have to replicate that entire 2%.  In my mind its similar to 
byte level replication (although an entirely different technology.)  Just 
because Netbackup backs up 20GB of "different" files doesn't mean that you've 
made 20GB of changes.  If that were the case I'd roll-over my file servers once 
a month.
 
I wonder after comparing the two technologies, if there is room for a "mixed 
mode" solution that could take advantage of both tape's and disk's benefits 
without creating a tough to swallow price tag.
 
-Jonathan

________________________________

From: veritas-bu-bounces AT mailman.eng.auburn DOT edu on behalf of Ed Wilts
Sent: Sat 9/22/2007 9:35 AM
To: 'Jeff Lightner'; veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Tapeless backup environments?



Here's some simple math that may help (complements of ExaGrid's web site).

 

If you have 1TB of data with a 2% change rate, you'll need to back up 20GB of 
daily incrementals.  To replicate this to another site in 18 hours requires 
3Mbps of bandwidth.  If you have lots of bandwidth or not too much data, 
replication to an offsite location may make sense.  But to think that you can 
replicate your backups for 20TB of data to another state is going to make your 
network group squirm.  Iron Mountain looks pretty cheap comparing to offsite 
electronic replication.

 

We have 1 application by itself that adds 30GB of new data every day.  It's 
being replicated within the metro area over a 1Gbps pipe (real time, not via 
backups).  We sure couldn't replicate everything...

 

As the OLD saying goes, never understand the bandwidth of a station wagon full 
of tapes.

 

               .../Ed

 

--

Ed Wilts, RHCE, BCFP, BCSD

Mounds View, MN, USA

mailto:ewilts AT ewilts DOT org

 

From: veritas-bu-bounces AT mailman.eng.auburn DOT edu 
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of Jeff 
Lightner
Sent: Friday, September 21, 2007 8:44 AM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] Tapeless backup environments?

 

Yesterday our director said that he doesn't intend to ever upgrade existing STK 
L700 because eventually we'll go tapeless as that is what the industry is 
doing.   The idea being we'd have our disk backup devices here (e.g. Data 
Domain) and transfer to offsite storage to another disk device so as to 
eliminate the need for ever transporting tapes.

It made me wonder if anyone was actually doing the above already or was 
planning to do so?


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