Re: Diff between "controlfile autobackup" and "snapshot controlfile"
- From: Jared Still <jkstill@xxxxxxxxx>
- To: Koen.Van_Langenhove@xxxxxxxxxxx
- Date: Thu, 3 Feb 2005 18:25:43 +0000
According to the fine manual, that isn't quite it either. :)
You can back up the control file when the database is mounted or open.
RMAN uses a snapshot control file to ensure a read-consistent version.
If CONFIGURE CONTROLFILE AUTOBACKUP is ON (by default it is OFF), then
RMAN automatically backs up the control file and server parameter file
after every backup and after database structural changes. The control
file autobackup contains metadata about the previous backup, which is
crucial for disaster recovery.
If the autobackup feature is not set, then you must manually back up
the control file in one of the following ways:
* Run BACKUP CURRENT CONTROLFILE
* Include a backup of the control file within any backup by using
the INCLUDE CURRENT CONTROLFILE option of the BACKUP command
* Back up datafile 1, because RMAN automatically includes the
control file and SPFILE in backups of datafile 1
A manual backup of the control file is not the same as a control file
autobackup. In manual backups, only RMAN repository data for backups
within the current RMAN session is in the control file backup, and a
manually backed-up control file cannot be automatically restored.
On Thu, 03 Feb 2005 11:48:58 +0100, Koen Van Langenhove
<Koen.Van_Langenhove@xxxxxxxxxxx> wrote:
>
>
> Mladen Gogala wrote:
>
> >Sam Reddy wrote:
> >
> >
> >
> >>Why there are two of these options ?
> >>
> >>
> >>
> >>
> >>
> >There is no difference. Those two options both produce a backup of
> >controlfile which
> >can be used to recover database using backup controlfile. The two
> >options are here
> >to confuse the enemy.
> >
> >
> >
> Well, I had this slightly different opinion .. the snapshot controlfile
> is a backup creates before the actual backup starts in order to have a
> 'read consistent' view of the controlfile during the backup. The
> controlfile autobackup is the 'regular' backup of the controlfile and it
> is created after the datafile and eventually archivelog backups. I read
> this in R. Freeman's book 'RMAN backup and recovery' ..
>
> So I agree with Mladen that both can be used in recovery operations, but
> I think there's more to it than just confusing the enemy ;)
>
> --
> Regards,
> Koen
>
> Siemens ICM/ICN
> IC MN D IS
>
> Phone : +32 14 25 3000
> Email : Koen.Van_Langenhove@xxxxxxxxxxx
> - - - - - - -
> Unix IS user-friendly .., it's just quite picky about its friends.
>
> --
> //www.freelists.org/webpage/oracle-l
>
--
Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist
--
//www.freelists.org/webpage/oracle-l
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