The Boss wrote:
> 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
>
Addendum:
An even more thorough explanation is given in the Concepts Guide:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/backrec.htm
(near the end, under heading "Overview of Instance and Crash Recovery")
at the end of which it also refers to the Backup and Recovery Advanced
User's Guide:
http://download.oracle.com/docs/cd/B19306_01/backup.102/b14191/toc.htm
"for a discussion of instance recovery mechanics and instructions for tuning
instance and crash recovery."
--
Jeroen
Received on Sat Jul 07 2007 - 13:29:03 CDT
