RE: RMAN - Some basic Qs.
Vivek, Answers to your questions embedded. You may want to read up on the manuals for more details. BTW, you don't have to copy my e-mail id in your replies, given that I belong to the list, just as many others. I am trying to avoid getting 2 copies of every e-mail that you send. Cheers, Gaja --- VIVEK_SHARMA [EMAIL PROTECTED] wrote: Gaja , Good indeed to see you back on the List . My Qs. in CAPITALS below :- -Original Message- Sent: Wednesday, April 02, 2003 2:14 AM To: Multiple recipients of list ORACLE-L 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. IS BACKUP DATA AS AT POINT-OF-TIME OF START OF RMAN BACKUP ? IF SO , HOW IS DATA INTEGRITY ACROSS DATAFILES MAINTAINED ? HOW ARE BLOCK DATA VALUES AS AT POINT OF BACKUP MAINTAINED WITHOUT STOPPING DMLs TO IT ? Gaja: There is no concept of backup data at point-of-time start of the RMAN backup. Backups as such do not require read consistency. A recovered tablespace/database requires consistency. This consistency is achieved by recovering the datafile or the entire database (if relevant) to the point noted in the controlfile, using the relevant online and archived redo logs. Ofcourse things are different for incomplete recovery scenarios. The backup is done whenever it is done. Again, the issue of consistency arises only when a recovery is done. In the case of hot backups or RMAN backups, the redo generation continues during the backup (as required) and the issue of consistency is dealt with when recovery is performed. With hot backups, Oracle plays it safe and generates more redo, to protect against block-fracture on the backed-up files. This is required due to the 512-byte read-chunk-size that OS utilities use, which is different than DB_BLOCK_SIZE on most databases. This not relevant in RMAN backups due to DB_BLOCK_SIZE read-chunk-size and the relevant synchronization methods that RMAN uses. 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. MY UNDERSTANDING OF HOT BACKUP :- ASSUME 1 TABLESPACE HAS 2 DATAFILES DMLs HAPPENING ONLY TO FILE 2. AFTER SWITCHING TABLESPACE TO BEGIN BACKUP . ASSUMING SEQUENTIAL O.S. BACKUP OF DATAFILES , WHILE BACKUP OF THE 1ST FILE IS UNDERWAY , BEFORE IMAGES OF ALL DMLs HAPPENING TO FILE 2 ARE BEING ARCHIVED . THEREAFTER FILE 2 IS BACKED UP . FINALLY TABLESPACE END BACKUP IS ISSUED. THUS USING THE BEFORE IMAGES OF BLOCKS OF FILE 2 , THE TABLESPACE CAN BE BROUGHT TO DATA EXISTING AS AT POINT OF START OF HOT BACKUP. Gaja: See previous explanation. Your understanding is not fully accurate, please read the manuals for more details. Basically, it is OK for the backup copy of File#1 to be different from File# 2. The issue of consistency is dealt with during recovery and Oracle does a great job of it, by dealing with the logs that need to be applied, on a per file basis. Hope that helps, Gaja ==stuff deleted== = __ Do you Yahoo!? Yahoo! Tax Center - File online, calculators, forms, and more http://tax.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).
RE: RMAN - Some basic Qs.
Gaja , Good indeed to see you back on the List . My Qs. in CAPITALS below :- -Original Message- Sent: Wednesday, April 02, 2003 2:14 AM To: Multiple recipients of list ORACLE-L 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. IS BACKUP DATA AS AT POINT-OF-TIME OF START OF RMAN BACKUP ? IF SO , HOW IS DATA INTEGRITY ACROSS DATAFILES MAINTAINED ? HOW ARE BLOCK DATA VALUES AS AT POINT OF BACKUP MAINTAINED WITHOUT STOPPING DMLs TO IT ? 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. MY UNDERSTANDING OF HOT BACKUP :- ASSUME 1 TABLESPACE HAS 2 DATAFILES DMLs HAPPENING ONLY TO FILE 2. AFTER SWITCHING TABLESPACE TO BEGIN BACKUP . ASSUMING SEQUENTIAL O.S. BACKUP OF DATAFILES , WHILE BACKUP OF THE 1ST FILE IS UNDERWAY , BEFORE IMAGES OF ALL DMLs HAPPENING TO FILE 2 ARE BEING ARCHIVED . THEREAFTER FILE 2 IS BACKED UP . FINALLY TABLESPACE END BACKUP IS ISSUED. THUS USING THE BEFORE IMAGES OF BLOCKS OF FILE 2 , THE TABLESPACE CAN BE BROUGHT TO DATA EXISTING AS AT POINT OF START OF HOT BACKUP. 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,
RMAN - Some basic Qs.
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).
RE: RMAN - Some basic Qs.
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).
RE: RMAN - Some basic Qs.
Vivek 1. RMAN works on an entirely different principle than hot backups. Much more transparent to the database. 2. RMAN incremental backups work by checking if a block has changed since the last incremental backup of the current level or lower. So only changed blocks get backed up on an incremental. 3. According to some recent postings on this list, not very well. 4. Easy is in the eye of the beholder. If you own an MML, make sure your version is compatible with RMAN. If your organization has already paid the big bucks for the MML, get started making it work. If not, you may want to consider beginning by backing up to disk. Buy Robert Freeman's Oracle9i RMAN Backup Recovery. It covers MML integration. Dennis Williams DBA, 40%OCP, 100% DBA Lifetouch, Inc. [EMAIL PROTECTED] -Original Message- Sent: Tuesday, April 01, 2003 9:19 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: DENNIS WILLIAMS 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).
RE: RMAN - Some basic Qs.
No excessive Redo ...one of RMans new features.. I will have to write a book here to give you good answers... I would suggest reading the really good cheat sheet on technet on Backup and recovery...they are very good and complete.. If not that just search google for RMAN faq and you should Get you what you need. Brian -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: Spears, Brian 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).
Re: RMAN - Some basic Qs.
I need help, I have a procedure to insert xml data into a table. The xml data is store in CLOB, and i user xml parser and DOM to get the value and insert into table. If the file is is under 1 MB, everything is OK. But when the xml size is larger than 1 mb i'll get error message ORA-29532: Java call terminated by uncaught Java exception: java.lang.OutOfMemoryError BEGIN * ERROR at line 1: ORA-29554: unhandled Java out of memory condition I found 1 people in expert-exchange forum that have the same problem with me, and until now he dont have the solution. anyone here have experience with oracle xml parser. I already try to free the parser and document, and add more memory to java parameter, but this still not help. I read from metalink there is a bug like this in oracle 9i, but i'm using 8.1.7. I'm still looking for a way to fix this, before i run the pacth ( but i'm still not sure this will fix the problem) T.I.A __ 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: Bong 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).
RE: RMAN - Some basic Qs.
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 ? I found it to be fairly easy to get RMAN working with Legato NetWorker. We had to go through a few hoops to get it working on a Veritas Cluster, but the problems were related to implementing Legato NetWorker on the cluster rather than the RMAN/Legato interface. The setup and configuration is well documented. -Original Message- Sent: Tuesday, April 01, 2003 10:19 AM To: Multiple recipients of list ORACLE-L 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: Ed Bittel 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).
RE: RMAN - Some basic Qs.
Answer 1: RMAN keeps track of increasing SCNs of any changing datablock within the datafile being backedup. Hence not much redo. Answers to other questions have been posted by others. HTH GovindanK |XXX| |You should treat others the way you want to be treated - Mahatma Gandhi| |XXX| VIVEK_SHARMA [EMAIL PROTECTED] wrote: 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). __ Try AOL and get 1045 hours FREE for 45 days! http://free.aol.com/tryaolfree/index.adp?375380 Get AOL Instant Messenger 5.1 for FREE! Download Now! http://aim.aol.com/aimnew/Aim/register.adp?promo=380455 -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: 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).
RE: RMAN - Some basic Qs.
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).
Re: RMAN - Some basic Qs.
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 --
