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Home -> Community -> Mailing Lists -> Oracle-L -> RE: RMAN: What blocks are backed up with a full backup?
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.
dwilliams_at_lifetouch.com
-----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
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Author: DENNIS WILLIAMS
INET: DWILLIAMS_at_LIFETOUCH.COM
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