Difference between Instance recovery , Crash Recovery & Media Recovery ?
Here is the clear distinction between instance and crash recovery (from 9i backup and recovery concepts chapter 3):
"Crash recovery is used to recover from a failure either when a single-instance database crashes or all instances of an Oracle Real Application Clusters database crashes. Instance recovery refers to the case where a surviving instance recovers a failed instance in an Oracle Real Application Clusters database."
Specifically, if all the instances of a database is crashed then the term "crash recovery" applies. If at least one instance of the database is alive, then the term "instance recovery" applis. So, in case of a single instance (non-ops or non-rac), the term "crash recovery" does not apply.
In both, instance and crash recovery, there is no need for any manual intervention. No need to specify any archive log files etc.
On the contrary, Media recovery is performed by restoring a database file(s and applying the archivelog files manually using "recover" commands. Block level media recovery introduced in 9i might not need to restore entire file(s), but that is still considered as Media recovery.
Important distinction between Instance/Crash Recovery and Media recovery is that, media recovery needs manual intervention.
Here is the clear distinction between instance and crash recovery (from 9i backup and recovery concepts chapter 3):
"Crash recovery is used to recover from a failure either when a single-instance database crashes or all instances of an Oracle Real Application Clusters database crashes. Instance recovery refers to the case where a surviving instance recovers a failed instance in an Oracle Real Application Clusters database."
Specifically, if all the instances of a database is crashed then the term "crash recovery" applies. If at least one instance of the database is alive, then the term "instance recovery" applis. So, in case of a single instance (non-ops or non-rac), the term "crash recovery" does not apply.
In both, instance and crash recovery, there is no need for any manual intervention. No need to specify any archive log files etc.
On the contrary, Media recovery is performed by restoring a database file(s and applying the archivelog files manually using "recover" commands. Block level media recovery introduced in 9i might not need to restore entire file(s), but that is still considered as Media recovery.
Important distinction between Instance/Crash Recovery and Media recovery is that, media recovery needs manual intervention.
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