Init parameterBackup & recovery

DB_BLOCK_CHECKSUM

What it controls

Whether blocks carry a checksum that's verified on read.

Know this before you change it

Keep at least TYPICAL. FULL also checks blocks in memory, at a few percent of CPU.

Default: TYPICAL

Check and change it

1-- Current value on every instance2SELECT inst_id, name, value, isdefault, ismodified3FROM gv$parameter4WHERE name = 'db_block_checksum';5 6-- Value stored in the spfile7SELECT sid, value FROM v$spparameter WHERE name = 'db_block_checksum' AND isspecified = 'TRUE';8 9-- Dynamic: takes effect now and is kept after a restart10ALTER SYSTEM SET db_block_checksum = TYPICAL SCOPE = BOTH SID = '*';11 12-- Remove it from the spfile to go back to the default at the next restart13ALTER SYSTEM RESET db_block_checksum 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_CHECKINGLogical consistency checks on blocks when they change.
• DB_LOST_WRITE_PROTECTRecords block versions in redo so lost writes can be detected.