Oracle® Database Reference 10g Release 1 (10.1) Part Number B10755-01 |
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Property | Description |
---|---|
Parameter type | Boolean |
Default value | true |
Modifiable | ALTER SYSTEM |
Range of values | true | false |
Basic | No |
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. Checksums are verified when a block is read-only if this parameter is true
and the last write of the block stored a checksum. In addition, Oracle gives every log block a checksum before writing it to the current log.
If this parameter is set to false
, DBWn calculates checksums only for the SYSTEM
tablespace, but not for user tablespaces.
Checksums allow Oracle to detect corruption caused by underlying disks, storage systems, or I/O systems. Turning on this feature typically causes only an additional 1% to 2% overhead. Therefore, Oracle recommends that you set DB_BLOCK_CHECKSUM
to true
.