In case of hot backup scn at then time of starting backup is frozen in datafile header , and is refreshed at the time of end backup .what happens in RMAN ?
-ak ----- Original Message ----- To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> Sent: Tuesday, April 01, 2003 12:43 PM > All, > > The primary reason why RMAN does not generate > excessive redo is because because it does not put the > tablespace in "hot backup mode". Thus any blocks > belonging to a given tablespace that are modified > before the END BACKUP command is processed, do not > require block-level before and after images. Hence the > reduction in redo generation. > > So how does RMAN backup without "hot backups"? > > RMAN is aware of the format of an Oracle datafile, and > reads datafiles for the backup in DB_BLOCK_SIZE > chunks. This is not the case with most OS utilities > (tar, cpio, cp, dd etc.), which read files in 512-byte > OS blocksize chunks. > > As a result, the issue of a fractured block (for which > block-level before/after images are taken) on the > destination where the backup is done, does not come > into play in RMAN. > > Hope that helps, > > Gaja > > --- "Goulet, Dick" <[EMAIL PROTECTED]> wrote: > > 1: RMAN does not generate excessive redo because it > > does not use the 'alter tablespace ... begin backup' > > command. It instead coordinates with dbwr, somehow, > > to be sure it is getting a consistent view of the > > tablespace. > > > > 2: The concept of an incremental backup is that you > > only backup the database blocks that have changed > > since the last incremental of the same or higher > > level. Somehow the date that the block changed is > > being managed, probably in the header somewhere. > > > > 3: If your reading a block for backup purposes, it's > > pretty easy to checksum it and compare with what's > > in the header just like the Oracle kernel does. > > > > 4: I've tried before with OmniBack and it's fairly > > simple. You only have to relink Oracle including a > > MML library file. The package you want to integrate > > with should have instructions. > > > > Dick Goulet > > > > -----Original Message----- > > Sent: Tuesday, April 01, 2003 10:19 AM > > To: Multiple recipients of list ORACLE-L > > > > > > > > Qs.1 Why is NO excessive Redo Generated wsing RMAN > > Backups unlike HOT Backups > > when taking backup of an OPEN Database which is > > undergoing User Transactions ? > > (Or am i mistaken ?) > > > > Qs.2 How does RMAN manage Incremental Database > > Backups ? What is the Concept behing it ? > > > > Qs.3 How does RMAN Check for Block Corruption while > > taking backup ? > > > > Qs.4 Is it easy to integrate 3rd part tools like > > Legato etc with RMAN for enabling taking > > of backups onto backup devices OR does it need an > > extensive setup ? > > > > > > -- > > Please see the official ORACLE-L FAQ: > > http://www.orafaq.net > > -- > > Author: VIVEK_SHARMA > > 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). > > > > -- > > Please see the official ORACLE-L FAQ: > > http://www.orafaq.net > > -- > > Author: Goulet, Dick > > 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). > > > > > ===== > > > __________________________________________________ > Do you Yahoo!? > Yahoo! Tax Center - File online, calculators, forms, and more > http://platinum.yahoo.com > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.net > -- > Author: Gaja Krishna Vaidyanatha > 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). > > -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: AK 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).
