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RMAN backup fails on free space or un-used blocks (Doc ID 2876454.1)

Last updated on AUGUST 31, 2023

Applies to:

Oracle Database - Enterprise Edition - Version to 21.6 [Release 10.2 to 21.0]
Information in this document applies to any platform.
RMAN backup fails on free space or un-used blocks

Once you drop/truncate an object with a bad/corrupted block(s), the bad block(s) will be added to the free space list and in some cases still show in the RMAN validate.
A block is considered free if it is not allocated to any object or it is allocated to an object and never used. Oracle can allocate extents for an object to grow and the blocks are not used until data is inserted.

The reason you see the free space blocks in RMAN

RMAN reads the bitmaps stored in a locally-managed datafile header to deduce whether a particular extent is free or used. Based on how these bitmaps are managed and read by RMAN, its not always guaranteed that RMAN will skip all extents which are currently un-used. Some extents might still be read by RMAN for backups even though they are currently un-used. So we cannot be sure if RMAN will skip the extent belonging to the corrupt block or try to read it. If RMAN reads it, it will fail with error ORA-19566 due to the corrupt block RMAN backup will fail.

In some cases the free space blocks cannot be cleared. Option 5 is the best.


 Remove the free space blocks so RMAN backups can complete


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