A good Virtual Tape system will completely offload the task of media
management from your hosts. It will store it's own policies which
allow you to specify things like "keep this logical volume on disk for
7 days, and write two copies to tape immediately, one of which will be
sent offsite for a year".

NetBackup doesn't need to know anything about it. Why would you get
NBU and a host to do the duplication when there's a purpose built
system there that can handle it all with no impact to hosts.

It *is* a seperate point of management, and in a DR you would need to
recover your Virtual Tape system before you started restoring systems.
People from a mainframe background have been working this way for
decades.

In a multiple SAN media server with SSO environment, I would prefer to
deal with one centralised point of media management, rather than
dozens of media servers and trying to get SSO working nicely.

Of course if you use multiple types of backup software (CA, Tivoli,
whatever) which a lot of companies still do, a good VTS will allow you
to share your infrastructure between them all.

That's my 2cents worth!

On Fri, 28 Jan 2005 17:27:34 -0500, Paul Gimpelev <paulg AT cdcna DOT com> 
wrote:
> Kris,
> 
>         NetBackup does not know if VTL duplicates tapes out of the back.  This
> presents a problem - you can only have a single copy of the tape.  Say NBU 
> host
> wrote to tape VLT000 on the virtual library and that tape got duplicated
> through the back end to a physical LTO tape with label VTL000(has to be the
> same) then once the duplication is done VTL will erase it's own tape copy and
> only one on physical media will exist.  If you need to retain two copies of 
> the
> tape, one on-site the other off-site at the same time you will need to use NBU
> duplication through either Vault or manually.
> 
>         Using same cards for disk and tape is definitely not recommended by 
> any
> vendor I know.  You can, potentially, avoid the issue of limited PCI slots by
> using dual-port HBAs.
> 
>         As far as using NT 4.0 you will need to check with a specific VTL
> vendor, they may or may not support it.
> _______________________________________________
> Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
> http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu
>