BCT reads additonal blocks and performance of backup gets worse
(Doc ID 2636416.1)
Last updated on APRIL 17, 2023
Applies to:Oracle Database - Enterprise Edition - Version 18.104.22.168 and later
Information in this document applies to any platform.
When BCT (Block Change Tracking) is enabled, RMAN will only read changed blocks to include in the incremental backup.
However, if the lead blocks (*) of the datafiles have never been updated, the BCT will continuously read the updated blocks.
Due to this behavior, performance of incremental backup may get worse.
(*) lead blocks refers to the block whose block number is less than 983808 when using db_block_size=8k.
This problem may happen on following situation.
- BCT (Block Change Tracking) is enabled
- Lead blocks of datafile has never updated after getting incremental backup.
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