Sue -- You have a number of areas to study.  You should get an
understanding of the capabilities of your system (tape drive, cpu,
network and clients presenting data to the network) in terms of (1) what
is theoretically possible and (2) what you are seeing during the backups.

Learning about these two areas will allow you measure how you are doing
with respect to a theoretical maximum.  You probably won't reach the
maximums, but you'll have a better understanding of your system and
perhaps get ideas of where to focus.

Your actions should include "tuning".  Veritas has TechNotes on their
support web site to help.  In general, getting the most from your tapes
will mean maximum buffer size for the tapes and near maximum number of
buffers.  This allows for maximum performance of your tapes.  The tapes
can still be held back by the network, so this area should be looked
at.  Just a couple of clients with poor network settings, slow links or
being unreachable can wreak havoc with backup schedules, especially when
you have just once source stream for each tape.

Which brings us to multiplexing (MPX).  Multiplexing is your best friend
when your client systems can't get data to your backup system fast
enough to keep your tapes spinning.  They will impact restore times
(little impact for slow clients, perhaps significant impact to fast
clients), but they give you your best chance to complete backups in
minimum time.

With all that done, if you have a client with multiple independent data
sources that isn't using all of its network connection, multiple data
streams may help. (A lot of "if"s!).  Multiple data streams is enabled
in a policy and controlled at the client level with a master server
"client  attribute", possibly with the help of specifying "new stream"s
in the backup selection list of a client's policy.

With that done, you're into adjusting backup schedules, expectations
and/or hardware/methods.

Hope this helps!     cheers, wayne

Preece, Sue wrote, in part,  on 1/13/2005 5:02 AM:

>I'm currently running Netbackup Business Server ver 4.5 and have 2 tape
>drives available for backups.
>
>I have a policy which is configured to backup 2 drives on server, an
>approx total of 140gb, which is taking far to long to backup and is now
>stopping me carrying out duplicates.
>
>Would allowing multiple data streams help and if so how do i configure
>it.
>