Init parameterBackup & recovery

DB_BLOCK_CHECKING

What it controls

Logical consistency checks on blocks when they change.

Know this before you change it

MEDIUM or FULL catch in-memory corruption before it's written, at roughly 1 to 10 percent CPU. Test the cost on your workload first.

Default: FALSE

Check and change it

1-- Current value on every instance2SELECT inst_id, name, value, isdefault, ismodified3FROM gv$parameter4WHERE name = 'db_block_checking';5 6-- Value stored in the spfile7SELECT sid, value FROM v$spparameter WHERE name = 'db_block_checking' AND isspecified = 'TRUE';8 9-- Dynamic: takes effect now and is kept after a restart10ALTER SYSTEM SET db_block_checking = MEDIUM SCOPE = BOTH SID = '*';11 12-- Or for your own session only13ALTER SESSION SET db_block_checking = MEDIUM;14 15-- Remove it from the spfile to go back to the default at the next restart16ALTER SYSTEM RESET db_block_checking SCOPE = SPFILE SID = '*';

Related scripts

• Corrupt blocks found by RMANBlocks RMAN has flagged as corrupt. The view is filled by backups and by RMAN VALIDATE, so run a validate first if you haven't recently.

Open in the parameter referenceOracle's reference

More in Backup & recovery

• DB_RECOVERY_FILE_DESTLocation of the Fast Recovery Area, for archived logs, backups and flashback logs.
• DB_RECOVERY_FILE_DEST_SIZEThe most space the Fast Recovery Area may use.
• DB_FLASHBACK_RETENTION_TARGETMinutes of flashback logs to keep for Flashback Database.
• CONTROL_FILE_RECORD_KEEP_TIMEDays that reusable backup and archived log records stay in the control file.
• DB_BLOCK_CHECKSUMWhether blocks carry a checksum that's verified on read.
• DB_LOST_WRITE_PROTECTRecords block versions in redo so lost writes can be detected.