Also, RMAN can do incremental backups, copying only the blocks that changed since last backup..... More about all this in Oracle Manuals and in Robert's book.
- Kirti -----Original Message----- Sent: Thursday, January 16, 2003 10:04 PM To: Multiple recipients of list ORACLE-L Maria - Definitely faster. Often hot backups can generate additional redo. Dennis Williams DBA, 40%OCP Lifetouch, Inc. [EMAIL PROTECTED] -----Original Message----- Sent: Thursday, January 16, 2003 9:24 PM To: Multiple recipients of list ORACLE-L does this make RMAN hot backups faster or slower than when backing up file in backup mode? [EMAIL PROTECTED] wrote: > To better answer the original question, my understanding of this difference > is as under: > > Why do you put the tablespace in backup mode during normal hot backups > without RMAN? This is to avoid backing up "split blocks". Say, you have a > database with a block size of 16K. And that a block is in the process of > being backed up, with reads happening in chunks of say, 512 bytes. Assume > a user transaction updates this block while the backup is in progress. This > could result in an inconsistent version of the block being backed up, or > what is called as "split blocks". Putting a tablespace in backup mode, is > primarily, a flag which tells Oracle to copy the entire block into the redo > stream, and not just the changed vectors or deltas, which it would have > done otherwise. This is so that, in case of recovery, the entire block can > be read from the redo stream, and applied. Hence, this results in an > increase in the redo size during normal hot backups. > > RMAN however, does not place the tablespaces in hot backup mode. They use > the same read consistency mechanism used by the SQL statements. Hence, no > excessive redo is generated. > > Hope this helps. > > Raj > > ----Original Message----- > Sent: Thursday, January 16, 2003 1:54 PM > To: Multiple recipients of list ORACLE-L > > Rman uses the same construct to get the right data in a hot backup as > sqlplus, the SCN of the database. It reduces excess redo because you don't > have to put the datafile in backup mode with a begin backup and take it out > > with and end backup. > > HTH, > Ruth > ----- Original Message ----- > To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> > Sent: Thursday, January 16, 2003 12:35 PM > > > > > Is Excessive Redo Generated during RMAN OPEN Database backup using backup > > sets as happens in case of HOT Backup ? > > > > If NOT , Why ? > > > > -- > > Please see the official ORACLE-L FAQ: http://www.orafaq.net > > -- > > Author: VIVEK_SHARMA > > INET: [EMAIL PROTECTED] > > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.net > -- > -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Deshpande, Kirti INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
