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Alter Database Begin backup flow (merged) [message #421180] Sat, 05 September 2009 01:28 Go to next message
paradoxkhan
Messages: 92
Registered: April 2008
Location: Pakistan
Member

Hi,

We have 24x7 production environment oracle 10g(10.2.0.1) running on solaris 10. We have to take hot backup of our production every night and restore it to another production reporting server.
The steps we follow to take backup on production is

1) " Alter database begin backup "
2) Copy datafiles, control files, redo.
3) Restore it on reporting server and initiate recovery.

But the time we initiate recovery on reporting server it fails with error.
"Control file is recent then datafile and vise verse).

My question is that what actually " Alter database begin backup do"

1) Freeze Datafiles?
2) Update control file or not?
3) How all headers are sync after end backup?

I would really appreciate if any one can help me understand the complete flow of Alter database begin backup.

Thanks,
Yasir

Re: Alter Database Begin backup flow [message #421182 is a reply to message #421180] Sat, 05 September 2009 01:43 Go to previous messageGo to next message
Michel Cadot
Messages: 64103
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
1) begin backup
2) copy files
3) end backup
4) switch and archive current log
4) copy control files and archived logs generated during copy

Other questions answered in Database Concepts.

Also read Wiki page User Managed Online Backups.

Regards
Michel
Re: Alter Database Begin backup flow (merged) [message #421183 is a reply to message #421180] Sat, 05 September 2009 01:45 Go to previous messageGo to next message
Michel Cadot
Messages: 64103
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
DO NOT crosspost your questions.

Regards
Michel
Re: Alter Database Begin backup flow (merged) [message #424425 is a reply to message #421180] Fri, 02 October 2009 05:27 Go to previous messageGo to next message
mohd_dba
Messages: 19
Registered: October 2009
Junior Member
If it is 24*7 database and you need to take the backup.Online backup is possible.

Conditions : 1.Archivelog should be enable.
2.Ensure that all online redologs are archived either by automatically or manually by using alter system archive log sequence.

If we put the tablespace in begin backup mode oracle enables to backup all the datafiles or single datafile for a particular tablespace.Single DBF can be used to be taken to minimize the time in which the files are written in Fuzzy state.

While coming in a Fuzzy state SCN block of a Oracle datafile header may be inconsistent with the SCN of a datafile header.

When we put the tablespace in begin backup mode.A checkpoint is performed on all the datafiles of the tablespace.All the changes made in memory by tablespace and upto that point is recorded in datafiles.

Note:It freeze the datafile header and sequence in the datafile header from changing.Redologs are applied for media recovery for the time to open database backup started.

Alter tablespace <tbs name> begin backup.

Go to os level and backup that DBF.

alter tablespace <tbs name> end backup.

select * from v$backup;

alter database backup controlfile to '/u01/oracle/oradata/satyam/hbk/control01.ctl';

In Oracle 10g.

alter database begin backup;
alter database end backup;

If I missed any more.Please include.

Thanks,
Afroze.
Re: Alter Database Begin backup flow (merged) [message #424426 is a reply to message #424425] Fri, 02 October 2009 05:44 Go to previous message
Michel Cadot
Messages: 64103
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
Do not put the whole database in backup mode, doing it tablespace per tablespace is a better option to prevent from too much redo log generation.

A complete description is in the link I previously posted.

Regards
Michel

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