| Oracle Hot backup [message #59412] |
Tue, 18 November 2003 01:57  |
Bala S
Messages: 4
Registered: November 2003
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Junior Member |
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Hi ,
I have a query on Oracle Hot backup on Oracle 8i.
How immediate should i take the backup of the control files after backing up the datafiles?
Iam not sure if there is any foolproof procedure for backing up the control file that corresponds to the backed up datafiles.
And what happens if the control file is changed/modified before i back it up?
Thanks in Advance,
Regards,
Bala S
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| Re: Oracle Hot backup [message #59413 is a reply to message #59412] |
Tue, 18 November 2003 02:12  |
Daljit Singh
Messages: 290
Registered: October 2003
Location: Texas
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Senior Member |
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Hi,
Well nothing will happen if after backing up the datafile control file get changed. See u r taking hot backups it means u r running ur DB in archivelog mode,
so u have the archive file which contains all the change vectors.
Suppose u have taked backup of datafile when the last or say highest SCN was 201 then due to some other transactions ur control file get updated with the latest SCN, in this scenario there is no need to worry at all bcz those transaction which r not in ur datafile will be there in ur archive files.
Moreover DB files will not be in consistent state whenever u take hot backups to get a consistent DB from hotback ARCHIVE files r used.
Thanx.
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| Re: Oracle Hot backup [message #59415 is a reply to message #59413] |
Tue, 18 November 2003 02:32 |
Bala S
Messages: 4
Registered: November 2003
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Junior Member |
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Thanks Daljit,
But my worries still remain w.r.to the following:
After backing up the datafiles using o.s. commands, i do a "alter tablespace <name> end backup".
Now from this point of time till the control file is backed up , the control file is vulnerable to change apart from the SCN update. (like a new tablespace is created in another session).
In that case will i have a chance to recover the database from the datafiles and the changed controlfile.
Pls. help.
Thanks again for your reply.
Regards,
Bala S
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| Re: Oracle Hot backup [message #59417 is a reply to message #59415] |
Tue, 18 November 2003 04:28 |
sachin kumar gupta
Messages: 157
Registered: March 2003
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Senior Member |
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Hi,
See u can't recover the database apart from datafiles & control files. You need & need the archived log files. Also, after end backup is issued first u backup ur control files. And then archive the current logs(alter archive log current;) & then immediately take backup of archived files.
Now, regarding changes in control file that u don't need to worry. Changes will occur only after control file has been backed up & when archive log current has been issued. This will be updated in control file(ALL SCN'S WHICH WAS UR QUESTION) at the time of recovery from archived log files .
If still u feel that u r not answered, pls. ask again!!
Regards,
Sachin
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| Re: Oracle Hot backup [message #59419 is a reply to message #59415] |
Tue, 18 November 2003 09:08 |
Thiru
Messages: 1089
Registered: May 2002
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Senior Member |
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Its a good idea to switch the logfile and backup the controlfile just after the hotbackup is complete. And once you backup all the archived redolog files that were generated during the hotbackup (including the switched one) , you have a complete working set that can be recovered without any issues.
-Thiru
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