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clarifications [message #322552] Sat, 24 May 2008 07:42 Go to next message
kesavansundaram
Messages: 181
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.
Re: clarifications [message #322555 is a reply to message #322552] Sat, 24 May 2008 08:27 Go to previous messageGo to next message
BlackSwan
Messages: 25039
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.
Re: clarifications [message #322566 is a reply to message #322552] Sat, 24 May 2008 09:09 Go to previous messageGo to next message
Michel Cadot
Messages: 64119
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
Re: clarifications [message #322588 is a reply to message #322552] Sat, 24 May 2008 11:50 Go to previous messageGo to next message
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.
Re: clarifications [message #324000 is a reply to message #322552] Fri, 30 May 2008 04:26 Go to previous message
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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