Understanding why an RMAN incremental backup will suddenly increase in size

(Doc ID 1273492.1)

Last updated on OCTOBER 27, 2016

Applies to:

Oracle Server - Enterprise Edition - Version: 10.2.0.4 and later   [Release: 10.2 and later ]
Information in this document applies to any platform.

Goal

Sometimes, an RMANincremental backup takes much longer than expected and creates a backuppiece that is a big as a full or level 0 incremental backup.

To understand what is going on, v$backup_datafile should be queried for all backups in the current backup cycle ie from the previous level 0 backup to current:

SQL>set lines 800
SQL>set pages 100
SQL>alter session set nls_date_format='dd-mon-rr hh24:mi:ss';
SQL>select recid, file#, to_char(creation_change#), incremental_level, to_char(incremental_change#) inc#,to_char(checkpoint_change#) ckp#, datafile_blocks BLKS, block_size blksz, blocks_read READ,
round((blocks_read/datafile_blocks) * 100,2) "%READ",
blocks WRTN, round((blocks/datafile_blocks)*100,2) "%WRTN",
completion_time, used_change_tracking
from v$backup_datafile where completion_time > 'date';

Sample output  (edited, and for file#1 only):

FILE#   CREATION_CHANGE# LVL                INC#        CKP#                     TIME          %Wrtn
1           8                                                                         0      6541999900034     28-Nov-10   88.86
1           8                                          2                             8      6542006129555     30-Nov-10   88.94
1           8                                          2     6542006129555      6542013100819     30-Nov-10     4.47
1           8                                          2    6542013100819       6542025661065      01-Dec-10    4.12
1           8                                          1                            8       6542032339845      03-Dec-10   89.05



Solution

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