What it doesn't write are the blocks that are not allocated to any extent. RMAN doesn't go into the logical structures, like tables and indexes, it looks into the tablespace header and reads the information from the bitmap information there. It cannot go into tables/indexes because it should also work when the database is only mounted and not opened, which genrally means that data dictionary is not accessible. Empty blocks are blocks that don't have any rows in them but are allocated to an extent. New or unallocated blocks are blocks that have been initialized when the datafile was allocated to the tablespace but have not been assigned to any object (table, index, materialized view, cluster, partition or alike)
-----Original Message----- Sent: Thursday, April 03, 2003 4:24 PM To: Multiple recipients of list ORACLE-L Actually this is how RMAN works. It writes all blocks up to the HWM of a given table, even empty ones. So, if your HWM is artifically high, you will encounter backups that are larger than they need to be. Oracle9i RMAN Backup and Recovery.... On bookshelves now! RF -----Original Message----- To: Multiple recipients of list ORACLE-L Sent: 4/3/2003 11:19 AM Keith Here is my understanding (don't rely on this one). When Oracle allocates tablespace, the disk blocks are cleared. My interpretation is that when RMAN encounters a clear block, it doesn't write it to the backup piece. I don't think it spends a lot of time trying to figure out above HWM and such. Dennis Williams DBA, 40%OCP, 100% DBA Lifetouch, Inc. [EMAIL PROTECTED] -----Original Message----- Sent: Thursday, April 03, 2003 10:44 AM To: Multiple recipients of list ORACLE-L Our RMAN backup is backing up much more than the actual data blocks when doing a full backup. I know that it backs up all blocks that have "ever been used", but I'm trying to figure out exactly what that means. My first thought was that it backs up all blocks below the HWM, but I analyzed the tables and that is not the case. Sometimes it backs up more blocks than exist below the HWM for the tables and sometimes it backs up fewer blocks than those below the HWM. We are doing this to determine what we can do to reduce the size of the backup. Anyone have an idea how this works? Keith -- 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). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Freeman Robert - IL 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: Gogala, Mladen 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).
