You may want to search the NetBackup mailing list archives. I did some testing 
2-3 years ago with LTO2 and LTO3 drives and posted the results. (Search for 
"fragment lto2 lto3".)

Offhand, from what I recall 10 GB fragments worked best for LTO3 and 6 GB 
fragments best for LTO2 - in our environment. You need to do the standard 
network buffer tuning first. Your disk read speeds and network speed and frames 
will also have an impact. 

The basic problem is that the old standard sized buffers don't let the drive 
get up to speed. The LTO drives seem to take about 6 seconds to ramp up to 
their full write speed. I saw that a 1 GB fragment would cause the drive to 
ramp up for about 3 seconds then start ramping down. Then it repositions...

Also keep in mind that if you have too many fragments on tape to search 
through, that may cause tape seek to take longer than by using larger but fewer 
fragments.

Bryan

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