The terms Cloning and Export from VTL vendors generally mean one or more of the following:
1. The VTL duplicates the contents of a virtual tape to another virtual tape (that may reside in a different VTL, perhaps in a DR site.), without NetBackup knowing.
2. The VTL duplicates the contents of a virtual tape to a physical tape through a tape library/drive that is directly under the control of the VTL, without NetBackup knowing. (In this case NetBackup may not even know about the existence of the physical tape library/drive because it is only connected to the VTL and not to NetBackup)
3. When NetBackup issues an eject command against a virtual tape, the VTL duplicates the virtual tape to a physical tape then ejects it, giving the illusion that it is not a VTL, but a physical tape library. Some VTLs may then also proceed to delete the contents of the virtual tape.
Allowing the VTL to handle backup duplication in such ways is not desirable because NetBackup would then lose track and control over where, when, how and what images are duplicated, and their number of copies.
It is best not to use such VTL features and simply let the equivalent (and better) NetBackup features (such as SLP, in-line copy, Vault duplications) to handle duplications and offsite copies.
You will find everything about this topic from this document:
NetBackup Whitepaper - Using VTL with NetBackup
http://eval.symantec.com/mktginfo/enterprise/white_papers/b-whitepaper_using_virtual_tape_libraries_with_netbackup_04-2009.en-us.pdf
I would recommend reading the whole whitepaper, but the part that discusses specifically about this issue starts from:
Can I Use the VTL Software to Copy Virtual Media to Physical Tape?
