If you are using the NetApp VTL to directly create physical tape, ie the VTL writes to the physical tape drive, then we have a list of certified physical tape drives and libraries that have been tested with our VTL product. This testing is similar to the way all vendors create a compatibility matrix to show what has been tested and certified. The NetApp VTL is compatible with 99% of the tape libraries on the market. If your particular library is not listed, just contact your NetApp Sales team and they can get the VTL business team to run the certification tests for your library.
If you are not using the VTL to directly create physical tape, then the compatibility list is moot as the VTL can create any type of emulated virtual library.