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Backup Mode [message #473497]

Sun, 29 August 2010 11:17

subbu_tce
Messages: 98
Registered: July 2007
Location: pune

Member

Hi,
My Tablespace is in backup mode.Now am issuing alter system checkpoint.will the dbwr writes the dirty blocks in datafiles.
If so,how it will update the scn becuase i havn't issued end backup still.Plz clarify me on this.

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Re: Backup Mode [message #473501 is a reply to message #473497]

Sun, 29 August 2010 11:53

Michel Cadot
Messages: 68653
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
Account Moderator

Yes.
The same thing than other tablespaces except that the header is not refreshed (and so the checkpoint scn).

Regards
Michel

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Re: Backup Mode [message #473529 is a reply to message #473497]

Mon, 30 August 2010 01:24

Yasir Hashmi
Messages: 304
Registered: April 2006

Senior Member

Hi,
The file would not be checkpointed.It was already checkpointed by a tablespace checkpoint when you put it in begin backup mode so header is freezed. The file would be available for normal operations but no checkpoint info would be recorded in its header until you put it in end backup mode.

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Re: Backup Mode [message #473530 is a reply to message #473529]

Mon, 30 August 2010 01:30

Michel Cadot
Messages: 68653
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
Account Moderator

Quote:

The file would not be checkpointed.

Yes and no. This is ambiguous.
The tablespace data blocks are flushed out the SGA to the tablespace files (which is the meaning of checkpoint), so for this point it is checkpointed.
But the file header is not updated and so the checkpoint scn is not marked (and so for the file point of view, it is not checkpointed.

This is why I said, the ONLY difference with other tablespaces is that the file header is not updated.

Eegards
Michel

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Re: Backup Mode [message #473532 is a reply to message #473530]

Mon, 30 August 2010 01:36

Yasir Hashmi
Messages: 304
Registered: April 2006

Senior Member

The file would not be checkpointed

, I only meant SCN would not be updated in file header.
But you are right.
Thankyou for correcting me all the time. Smile

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Re: Backup Mode [message #473539 is a reply to message #473532]

Mon, 30 August 2010 02:21

Michel Cadot
Messages: 68653
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
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To precise it using Oracle background processes implementation, DBWR does its checkpoint work, CKPT does not (on tablespace in backup mode).

Regards
Michel

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Re: Backup Mode [message #473544 is a reply to message #473539]

Mon, 30 August 2010 02:44

Yasir Hashmi
Messages: 304
Registered: April 2006

Senior Member

IS it so?
You mean when we issue alter tablespace begin backup command,its DBWR and not CKPT that freezes the header?

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Re: Backup Mode [message #473545 is a reply to message #473544]

Mon, 30 August 2010 03:16

Michel Cadot
Messages: 68653
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
Account Moderator

I mean during checkpoint after begin backup, DBWR still does the checkpoint (write the buffers for the tablespace) but CKPT does not (does not update the file header).

Regards
Michel

[Updated on: Mon, 30 August 2010 03:17]

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Re: Backup Mode [message #473556 is a reply to message #473545]

Mon, 30 August 2010 04:50

Yasir Hashmi
Messages: 304
Registered: April 2006

Senior Member

Thats true!!

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