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Re: Crash/instance recovery

From: The Boss <usenet_at_No.Spam.Please.invalid>
Date: Sat, 7 Jul 2007 20:17:23 +0200
Message-ID: <468fd8b5$0$321$e4fe514c@news.xs4all.nl>


DA Morgan wrote:
> astalavista wrote:
>> Hi,
>>
>> What is the difference between crash recovery and instance recovery ?
>>
>> Thanks for your lights ...
>
> You can not recover an instance ... an instance is processes in
> memory.

This article on OTN doesn't seem to agree with you: http://www.oracle.com/technology/deploy/availability/htdocs/std_recovery.html

<quote>
Automatic Fault Recovery
Oracle performs recovery automatically on two occasions:

At the first database open after the crash of a single-instance database or all instances of an Oracle Real Applications Cluster database (crash recovery).
When some but not all instances of an Oracle Real Application Clusters configuration fail (instance recovery). The recovery is performed automatically by a surviving instance in the configuration. The important point is that in both crash and instance recovery, Oracle will automatically recover data to a transactionally consistent state. This means the datafiles will contain all committed changes, and will not contain any uncommitted changes. Oracle returns to the transactionally consistent state by rolling forward changes captured in the log files but not the datafiles, and rolling back changes that had not been committed. This roll forward and roll back process is called crash recovery. In a Real Application Clusters environment, this process is performed by a surviving instance and called instance recovery.
<...>
</quote>

HTH

-- 
Jeroen


>
> You mean database recovery and they may or may not be the same in that
> there are more reasons to recover a database than just following a
> crash.
Received on Sat Jul 07 2007 - 13:17:23 CDT

Original text of this message

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