>Thanks Sonny and all who have replied. I'm still unclear about two things.
>
>  1 Is NBU's performance detrimentally effected when backing up lots
>    of small files over a view large ones?

it's the nature of the beast, not just some sort of flaw in Netbackup 
- the inherent overhead of reading/traversing the directory 
structure, writing the filenames to the index DB, etc means that a 
single 1 GB file will always back up substantially faster than 1024 
files that are each 1 MB in size...with ANY backup tool.  Unless you 
are backing up the raw filesystem, as a previous poster has suggested 
to you in the form of the FlashBack product.

(can anyone attest to the quality of the solaris FlashBack product? 
I'd love to talk to someone with direct experience with it in 
production...)

>  2 A few of you suggest that Multi Streaming to a single Volume is a
>    good thing to do. Whilst not wanting to sound argumentitive my
>    observation is that this will surely cause disk thrashing and
>    consequently always cause the backup to be slower ie single stream
>    to same disk will always be faster than multiple stream.

You're absolutely correct that this is a risk to be watchful for - 
but so many people are accessing their large datasets via a RAID 
subsystem, so usually there's multiple spindles that can probable 
handle multiple backup simultaneously.  YMMV - as always, you should 
test-tweak-and-repeat, doing all you can to guarantee that your tape 
drives become the bottleneck...

rob