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clarifications [message #322552]

Sat, 24 May 2008 07:42

kesavansundaram
Messages: 183
Registered: October 2007
Location: MUMBAI

Senior Member

dear sir,
i have one clarification

1.
when we put one tablespace in backup mode,
( alter tabelspace <.> begin backup;)
why redo is getting generated more ?

thank you
kesavan.

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Re: clarifications [message #322555 is a reply to message #322552]

Sat, 24 May 2008 08:27

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

Normally just change vectors get written to redo file.
When tablespace in backup mode whole DB blocks get written for every block under going DML.

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Re: clarifications [message #322566 is a reply to message #322552]

Sat, 24 May 2008 09:09

Michel Cadot
Messages: 68650
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
Account Moderator

http://download.oracle.com/docs/cd/B10501_01/server.920/a96572/osbackups.htm#7565

Regards
Michel

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Re: clarifications [message #322588 is a reply to message #322552]

Sat, 24 May 2008 11:50

varu123
Messages: 754
Registered: October 2007

Senior Member

Quote:

When tablespace in backup mode whole DB blocks get written for every block under going DML.

Only the first time the block is modified.Subsequent modifications of the same block requires just the changed bytes to get copied to redo log files.

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Re: clarifications [message #324000 is a reply to message #322552]

Fri, 30 May 2008 04:26

Rajabaskar Thangaraj
Messages: 13
Registered: March 2008
Location: CHENNAI

Junior Member

Refer the below link.

http://advait.wordpress.com/2008/05/27/excess-redo-log-generation-during-hot-backup-oracle-9i/

http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:894628342039

Thanks
RajaBaskar

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