IMHO, if you must move from TSM to Veritas NetBackup, (typically a
bureaucratic or
economic reason, not technically based) just start using NetBackup
and stop using TSM.  Then keep TSM running on a 'warm' server, and test
restores and migtating from tape to tape occasionally.  You can pretty much
get rid of the disk pools, but you will need to keep TSM 'alive' and ready
to
restore until you are ready to call it 'dead' for your use.

I hope you never have to do this.  But this is how we migrated from Veritas
BackupEXEC
to TSM, and given our 60 day retention window, it was acceptable.  This is
also how
a IBM VAR is suggestion we migrate to a new TSM server (from Windows to
AIX), but that
seems odd to me.

... Jack