It is not recomended to use tapes from a zone. For example we use NetBackup to backup out servers and it is recommended that the program run on the global zone. They also recommend not using a zone...
Take a look here: General Non-Global Zone Limitations (System Administration Guide: Oracle Solaris 9 Containers) (http://docs.oracle.com/cd/E19683-01/820-4490/gfudt/index.html)