保护级别在11g 中有所提升。
不仅在single instance 中此参数能有效减少
ORA-01578: ORACLE data block corrupted()
ORA-01110: data file ...
错误，还能在data guard 起到保护数据的功能。
建议在single instance 中设置 db_ultra_safe=DATA_ONLY在 data guard 中设置为 db_ultra_safe=DATA_AND_INDEX
由于此参数和其他3 个参数 DB_BLOCK_CHECKING/DB_LOST_WRITE_PROTECT/DB_BLOCK_CHECKSUM 有互斥作用，所以其他参数设置为default 或 在下表中建议的值。
---此参数对CPU 的使用会增加 10%或更多，请注意cpu资源紧张时慎用。
| Property | Description |
|---|---|
| Parameter type | String |
| Syntax | DB_ULTRA_SAFE = { OFF | DATA_ONLY | DATA_AND_INDEX } |
| Default value | OFF |
| Modifiable | No |
| Basic | No |
DB_ULTRA_SAFE sets the default values for other parameters that control protection levels.
Values:
-
OFF
When any of DB_BLOCK_CHECKING, DB_BLOCK_CHECKSUM, or DB_LOST_WRITE_PROTECT are explicitly set, no changes are made.
-
DATA_ONLY
-
DB_BLOCK_CHECKING will be set to MEDIUM.
-
DB_LOST_WRITE_PROTECT will be set to TYPICAL.
-
DB_BLOCK_CHECKSUM will be set to FULL.
-
-
DATA_AND_INDEX
-
DB_BLOCK_CHECKING will be set to FULL.
-
DB_LOST_WRITE_PROTECT will be set to TYPICAL.
-
DB_BLOCK_CHECKSUM will be set to FULL.
-