-8020: Next volume required 

Explanation:

This error can occur in the following cases (among others):

...

                            a.      When backing up: there is no more space on the data carrier currently being used.

                            b.      When importing a data backup: not all the data carriers belonging to this data backup were specified.

                            c.      When importing a log backup: the database system requires the next data carrier of the log backup.

User Response:

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                            a.      Specify another data carrier.

                            b.      Complete the list of data carriers.

                            c.      Specify the next data carrier (if available) for the log backup or end the log backup import manually.

See also:

Concepts of the Database System, Backing Up and Restoring