It's not as complicated as you make it sound.

Like tape, you need to keep some overhead in free disk.

If you want to maximize the contiguous free disk available, then you
would bplable tapes as they expire and go back to scratch.
As you write to a scratch tape, the space that cart previously occupied
is released, so as you occupy more space with that tape, the data
previously on that tape is again available for use...the background
defragger will reclaim that space for a subsequent backup.

I'd like to know how this problem goes away with a de-duping "disk as
disk" target.

If you write an image to a "disk-as-disk" target, and later the
netbackup image expires, how are you "ahead" of the same position you'd
be in with a VTL when a tape expires?

Paul


-- 


> -----Original Message-----
> From: Clem Kruger [mailto:clem AT re-thinking-it DOT com] 
> Sent: September 24, 2007 12:20 PM
> To: Kevin Whittaker; Paul Keating; Curtis Preston; 
> VERITAS-BU AT mailman.eng.auburn DOT edu
> Subject: RE: [Veritas-bu] Script to label expired tapes in a VTL
> 
> 
> Hi All, 
> 
> This is exactly right. The space is not available!
> 
> Let us assume that you need to write an urgent backup to a 
> different set of tapes. Although there are tapes that have 
> expired, you may not have space on the DISK to write to those 
> tapes, your backup will fail. Now go back to the directors 
> and tell them you now need more space because it has become 
> so easy to create new tape drives as well as new tapes.
> 
> The administration becomes extremely difficult if you are not 
> using Vaulting. Especially in large environments where you 
> backup 10's of TB every night.
> 
> It is not that I have anything against VTL's, it is my 
> contention that if you want disk to disk, rather do that. It 
> is easier to manage. Why be bothered still managing "TAPE" 
> albeit virtual?
> 
> Kind Regards,
> Clem Kruger
====================================================================================

La version française suit le texte anglais.

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