DB_ULTRA_SAFE Parameter

DB_ULTRA_SAFE is a new parameter introduced in 11g. It provides an integrated mechanism to offer protection from various possible data corruptions. and provides critical high availability benefits for Oracle Database. Setting DB_ULTRA_SAFE initialization parameter will configure the appropriate data protection block checking level in the database. It will control DB_BLOCK_CHECKING, DB_BLOCK_CHECKSUM, and DB_LOST_WRITE_PROTECT.

DB_BLOCK_CHECKING controls whether or not Oracle performs block checking for database blocks.

DB_BLOCK_CHECKSUM determines whether DBWn and the direct loader will calculate a checksum (a number calculated from all the bytes stored in the block) and store it in the cache header of every data block when writing it to disk.

DB_LOST_WRITE_PROTECT enables or disables lost write detection. A data block lost write occurs when an I/O subsystem acknowledges the completion of the block write, while in fact the write did not occur in the persistent storage.

DB_ULTRA_SAFE Parameter can be set to 3 different values: OFF, DATA_ONLY and DATA_AND_INDEX. Default value is OFF.

Here are the descriptions of these values:

OFF: It will not change values of DB_BLOCK_CHECKING, DB_BLOCK_CHECKSUM and DB_LOST_WRITE_PROTECT if they are explicitly set, otherwise all of them will set to default values.

DATA_ONLY: It will set DB_BLOCK_CHECKING to medium, DB_LOST_WRITE_PROTECT to typical and DB_BLOCK_CHECKSUM to full.

DATA_AND_INDEX: It will set DB_BLOCK_CHECKING to full, DB_LOST_WRITE_PROTECT to typical, and DB_BLOCK_CHECKSUM to full.

The only difference between DATA_AND_INDEX and DATA_ONLY is DB_BLOCK_CHECKING. When DB_BLOCK_CHECKING is set to full, Oracle will do semantic checks for index blocks.

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AWS Big Data Specialist. Oracle Certified Professional (OCP) for EBS R12, Oracle 10g and 11g. Co-author of "Expert Oracle Enterprise Manager 12c" book published by Apress. Awarded as Oracle ACE (in 2011) and Oracle ACE Director (in 2016) for the continuous contributions to the Oracle users community. Founding member, and vice president of Turkish Oracle User Group (TROUG). Presented at various international conferences including Oracle Open World.

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