| Rman backup mechanism [message #481225] |
Tue, 02 November 2010 01:23  |
sekar52
Messages: 141
Registered: May 2010
Location: Mumbai
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Senior Member |
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Hi I want to know how Rman backs up database on a block by block basis.
Consider a situation in which DBWR is writing to a datafile.Now we are backing up the datafile using RMAN.RMAN reads the datafile block by block to avoid fractured blocks.But if DBWR updates rows in 5 blocks and RMAN copies 2 blocks after DBWR updated and 3 blocks before DBWR could write wont the backup be inconsistent???
What will happen if we restore the backup in this case?
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| Re: Rman backup mechanism [message #481234 is a reply to message #481225] |
Tue, 02 November 2010 02:04  |
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Michel Cadot
Messages: 68716
Registered: March 2007
Location: Saint-Maur, France, https...
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Senior Member
Account Moderator |
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A hot backup (a backup made when the database is open) is ALWAYS inconsistent, anyway you do it, this is why you have to also backup the archived logs generated during the backup.
Regards
Michel
[Updated on: Tue, 02 November 2010 02:04] Report message to a moderator |
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| Re: Rman backup mechanism [message #481247 is a reply to message #481234] |
Tue, 02 November 2010 03:21 |
sekar52
Messages: 141
Registered: May 2010
Location: Mumbai
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Senior Member |
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Then What is the advantage of taking backup with RMAN rather than taking it with begin backup mode.They say RMAn doesnt put database in backup mode..So how is archive log generation when we use RMAN for taking backup
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| Re: Rman backup mechanism [message #481248 is a reply to message #481247] |
Tue, 02 November 2010 03:30 |
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Michel Cadot
Messages: 68716
Registered: March 2007
Location: Saint-Maur, France, https...
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Senior Member
Account Moderator |
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There is no difference in log generation with RMAN as the instance does not know it is currently backed up.
The advantage is not in this, it is on ALL RMAN features which is not just to not put the database in backup mode.
Regards
Michel
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