Rewinding Tape Devices Before Opening and on Closing

The tape device that TAPEDEV specifies must perform a rewind before it opens and when it closes. The database server requires this action because of a series of checks that it performs before it writes to a tape.

When the database server attempts to write to any tape other than the first tape in a multivolume dbspace or logical-log backup, the database server first reads the tape header to make sure that the tape is available for use. Then the device is closed and reopened. The database server assumes the tape was rewound when it closed, and the database server begins to write.

Whenever the database server attempts to read a tape, it first reads the header and looks for the correct information. The database server does not find the correct header information at the start of the tape if the tape device did not rewind when it closed during the write process.