I would recommend that 2Gb is probably not a large enough fragment size, as 
that's barely
long enough for the drive to get up to speed. Figure 70MB/sec transfer rate 
(optimally),
and your drive is stopping every 4 minutes (roughly). Add multi-plexing and that
could be even more often, not to mention that it makes very little difference 
any more.
For single-stream backups nbu knows where to go to get a file for a 
single-file-restore,
and for multi-plexed images nbu needs to read the entire image anyway.

Admittedly it's unlikely that you're going to see 70MB/sec, but it's still not 
very much
time.

George


On Wed, 25 Jan 2006, Casoli Marco wrote:

> Hello
>
> Look at the Veritas-Document #262724 (How to optimally performance-tune
> systems with IBM Linear Tape-Open 2 drives)
> Notice: You must have enough physical und shared memory on your system.
>
> And your question: We use the follow fragmentsize (2000 MB)
>
> Marco Casoli
> IT-Systemspezialist
> Storage/Backup
>
>
> Genossenschaft Migros Ostschweiz
> Finanzen/Informatik
> Industriestrasse 47
> CH-9201 Gossau
>
>
>  _____
>
> Von: veritas-bu-admin AT mailman.eng.auburn DOT edu
> [mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu] Im Auftrag von Barber,
> Layne (Contractor)
> Gesendet: Mittwoch, 25. Januar 2006 14:45
> An: veritas-bu AT mailman.eng.auburn DOT edu
> Betreff: [Veritas-bu] recommended LTO2 drive fragment size?
>
>
> Any recommendations for the fragment size when using LTO2 drives? Any
> other tuning tips for a 5.1 setup using LTO2.
>
>