How to restore an rman backup without any existing control files

This week a came across the following very interesting scenario:

The customer made an RMAN online backup and saved it to an NFS location. Controlfile autobackup was on. During backup the backupset was written to that NFS location. The control file however was written to the controlfile autobackup location (i.e. a different location).

After that the customer destroyed all disk groups and re-installed the database servers.

Afterwards he tried to restore the database which failed because there was no controlfile in the backups at all. In order to make it worse the customer had no log files from the RMAN backup session, no DBID and no trace files whatever – including the alert.log. This leaved us with the following situation:

  • no autobackup anywhere
  • no older controlfile available
  • no snapshot controlfile available
  • no redo log available
  • no backup logfiles
  • no “backup controlfile to trace” information
  • no DBID
  • no alert.log

Under normal circumstances restoring the database from an rman backup without having any control file is impossible. In this article i will show you an approach you might use to restore the datafile anyway.

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