T 2.57 Inadequate storage of media in the event of an emergency

If data needs to be restored after it has been destroyed, then it is necessary in many cases to restore the backed up data on separate storage media first. This is especially necessary for more complex data structures, for example for databases, since data restoration does not always proceed smoothly or without error. If the storage capacity needed in case of an emergency is not reserved beforehand, then additional losses of data can occur during an emergency through hasty action.

Example:

In a company with a large database application, the database was reported to be inconsistent by the database management system (DBMS). As a result, the management system took the database out of operation and restored the last backup copy of the database in the production system. However, only the log files and configuration files of the apparently corrupt database were backed up beforehand. Through restoration, all changes to the data made since the last backup were lost since it was impossible to redo the changes due to a previously unknown error in the DBMS. An analysis of the log files and configuration files then revealed that the database was not actually inconsistent in the first place. If there had been enough disk space available to perform the reconstruction parallel to production, then the old productive system would have been ready for operation again without suffering a loss of data after detecting and eliminating the apparent inconsistency.