I can only echo what others, (particularly Richard Schuh, with his very good overview), has said.
We use VTAPE extensively and it really comes into it's own when you need a large number of concurrent drives and the data on the virtual tapes is small or indeterminate. Support from VSSI is absolutely "Gold standard". We also use external virtual tape systems (both IBM & Sun/STK). The main advantage of these is sharing with non-VM systems. Integrating these did take more effort and understanding than with VTAPE - mainly because of shared cataloguing issues and, in the case of Sun/STK, the inability to drive mounts directly from VM. For very small, local backups we may use virtual tapes for convenience but for any significant backups we use modern 40gb external tapes. Colin Allinson Amadeus Data Processing GmbH
