I recently spent several months looking at disk technologies.  Just
generally speaking here I found that Disk Based Backups (DSU/DSSUs) are
pretty young in Netbackup and there's quite a few issues that have to be
monitored and maintained to make them work correctly.  That aside, you
can't beat the price per GB/TB for raw disk storage versus a VTL.  From
a management perspective, VTLs I think are easier because media
management is so well defined in Netbackup.  I've got several Perl
scripts I use to manage my DSSUs but everything I need for media is
right there in the GUI.
 
As far as compression and block level conversion to different formats
etc I think you may be getting a few crossed signals.  I've heard quite
a few issues with older VTLs especially when people try and duplicate
their tapes onto VTLs.  I'd check with your hardware vendor, but as best
I can tell all those issues were on the "bleeding edge."
 
-Jonathan
 
 

________________________________

From: veritas-bu-bounces at mailman.eng.auburn.edu
[mailto:veritas-bu-bounces at mailman.eng.auburn.edu] On Behalf Of Sixbury,
Dan
Sent: Wednesday, April 11, 2007 10:04 AM
To: veritas-bu at mailman.eng.auburn.edu
Subject: [Veritas-bu] Virtual Tape library or backup to disk



Does anyone have any recommendations in regards to VTLs or disk pools,
etc. for backup?  I have seen a lot of stuff on the market, but I have
also heard where some people have found out later that some of the
technologies don't always work as smoothly as their slated. i.e. one
solution I have seen takes all of your data and compresses it into block
level format on a separate device, but if you want to restore the data
or back it up to tape, you have to first uncompress it to a readable
format and then copy to tape.  

Thanks. 

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