Datafile media recovery or media recovery is used when we need to recover datafile, controlfile or spfiles( server parameter file).Crash recovery is the recovery of a database in a single-instance configuration or an Oracle Real Application Clusters configuration in which all instances have crashed.Like crash recovery Oracle will not initiate media recovery on its own, it must be demanded by a DBA only.
RE: what is the difference between media recovery & cr...
Datafile media recovery or media recovery is used when we need to recover datafile controlfile or spfiles( server parameter file).Crash recovery is the recovery of a database in a single-instance configuration or an Oracle Real Application Clusters configuration in which all instances have crashed.Like crash recovery Oracle will not initiate media recovery on its own it must be demanded by a DBA only.
RE: what is the difference between media recovery & cr...
media failture involves a physical when reading from or writing to a file that is necessary fo the database to operate. media failure is the most serious type of failure and dba intervention requires. To recover database depends on the following: .backup method you choose and which files are affected. .the arechivelog mode of operation of the database. if archiving is used you can apply archived redo log files to recover committed data since the last backup. if you are using rman you can also apply incremental backups. instance failure: .power outage .hardware problems .background processes startup instance---- the oracel server will automatically recover performing both the roll forward and roll back phases. investigates the cause of failure by reading the alert log and any other trace files that were generated during the instance fuilure.
RE: what is the difference between media recovery & cr...
oracle never accepts the inconsistency of the database. so when oracle goes down due to power outage or aborted manually next time once the database base is opened it goes mainly to the three states nomount mount and open when oracle try to open the database it makes check of SCN in the controlfile and each database datafile header if the check is not correct it will try to perform crash recovery and apply the online redo logs to bring the database in consistent state. By any means if it could not apply then it will try to locate the archive logs to apply and asks for media recovery.
RE: what is the difference between media recovery & cr...
The basic diff between the media and crash recovery is that media recovery is performed by the user or dba with the helps of backups while the crash recovery is performed by the oracle itself by using his sman background process.
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