Used to use Arcserve, we now run Tivoli. As for trusting any tape device, I don't. Part of an Network Admins job is to worry about disk space. One of the main functions of any dba is to secure the database and make sure it is recoverable. So you need to do what you are comfortable with to make recovery easy and reliable. I personnally copy my cold backups to another server, along with my archive logs.