Crash and media recovery
In general, database recoveries can be categorized into two broad domains:
- Crash recovery
- Media recovery
Crash recovery (a.k.a. instance recovery) is a more subtle form of database recovery because all that is lost is the database instance. Since it's just the instance that's lost and not any physical file of the database, the recovery won't need any physical file(s) to be restored. The background process SMON will initiate the recovery automatically at the time of the next database startup. In this recovery, only the online redo logs belonging to a single thread (for a single instance) or of multiple failed threads are used for a Real Application Cluster (RAC) database.
Note
Many DBAs often use the terms instance and crash ...
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