This post tells the possible DB2 failures and how to resolve them. BACKUP and RESTORE data over several possible system problems:
System Failure: If the system holding the database crashes or stops working, all the data in it is lost. You cannot recover this data without a database backup.
Unpredictable Errors Invalid modifications made to a database by a client can corrupt the data. It is recommended that you backup data before making any changes to the database.
Server Failure: If the server stops working due to a natural disaster, a standby server should be activated immediately or a copy of the database should be restored on another server. BACKUP and RESTORE can be used to move or copy a database from one server to another. BACKUP makes a copy of the entire database, including the required sections of the transaction log. This copy can be used to restore the database, if the need arises.
To use BACKUP, you need to start the database manager. You should have SYSCTRL, SYSADM, or SYSMAINT authority. The database for which a backup is to be taken can be on a local or remote machine.
The lost information in the database can be brought back to its original condition by restoring the database. Incomplete transactions, if any, are rolled back. This guarantees the consistency of the database.
RESTORE is used to restore the data backed up with BACKUP. The database cannot be used until the restore process is complete. You can restore either to a new database or to an existing one.