We had a problem a bit like this with Networker.
When we checked the logs, it transpired that Networker was actually doing full backups even though we told it to do incrementals.
We came to the conclusion that the problem is that strictly speaking, NDMP doesn't support the concept of incremental backups (this was alluded to earlier in the thread). It supports either full, or multilevel differential backups.
To get the same effect as an incremental backup (we do a full backup each weekend and nightly incrementals), we had to manually create a schedule in Networker that specified the backup level numbers explicitly for each night to perform a differential backup against the previous night. This may well create additional overhead when you try to restore - given that we had to manually configure the differentials it's not clear to me if Networker is smart enough to know that it has to rebuild the full state from them - so if you end up doing this make sure you test it thoroughly.
My suggestion therefore is that you check your Netbackup configuration logs to see if it is simply doing full backups all the time.
It really is a shame that NDMP is treated rather like a poor second cousin by everyone involved. Given that EMC and others were involved in specifying NDMP, I was surprised that Networker, and apparently other major (and very expensive) enterprise backup tools, don't appear to have recipes for performing NDMP backups and restores along the lines of the industry standard, ie weekly full and daily incremental.
As always, YMMV ...
