To validate data and identify data that is corrupted, you can use a feature called logical block protection. If you use logical block protection, Tivoli® Storage Manager inserts a cyclic redundancy check (CRC) value at the end of each logical block of data to be written to tape.
About this task
With logical block protection, you can identify errors that occur while data is being written to tape and while data is transferred from the tape drive to Tivoli Storage Manager through the storage area network. Drives that support logical block protection validate data during read and write operations. The Tivoli Storage Manager server validates data during read operations.
If validation by the drive fails during write operations, it can indicate that data was corrupted while being transferred to tape. The Tivoli Storage Manager server fails the write operation. You must restart the operation to continue. If validation by the drive fails during read operations, it can indicate that the tape media is corrupted. If validation by the Tivoli Storage Manager server fails during read operations, it can indicate that data was corrupted while being transferred from the tape drive and the server tries the operation again. If validation fails consistently, the Tivoli Storage Manager server issues an error message that indicates hardware or connection problems.
If logical block protection is disabled on a tape drive, or the drive does not support logical block protection, the Tivoli Storage Manager server can read protected data. However, the data is not validated.
Logical block protection is superior to the CRC validation that you can specify when you define or update a storage pool definition. When you specify CRC validation for a storage pool, data is validated only during volume auditing operations. Errors are identified after data is written to tape.
Drives that support logical block protection
Logical block protection is available only for 3592, LTO, and ECARTRIDGE device types. Capable 3592 drives include IBM TS1130, TS1140, and later generations. Capable LTO drives include IBM LTO-5 and supported LTO-6 drives. Capable Oracle StorageTek drives include drives with the T10000C and T10000D format.- Enabling and disabling logical block protection
You can specify logical block protection for read and write operations, or only for write operations. You can also disable logical block protection if it is enabled. By default, logical block protection is disabled because of performance effects that result from CRC validation on the server and the tape drive. - Read/write operations to volumes with logical block protection
Read/write operations to empty or filling volumes depend on whether the volumes have logical block protection. Protected and unprotected data blocks cannot be mixed on the same volume. - Storage pool management
To mix protected and unprotected data in a library, you must create different device classes and different storage pools to separate the data. The device classes associated with the protected data can specify logical block protection for read/write operations or only for write operations. 
Drives that support logical block protection
Logical block protection is available only for 3592, LTO, and ECARTRIDGE device types. Capable 3592 drives include IBM TS1130, TS1140, and later generations. Capable LTO drives include IBM LTO-5 and supported LTO-6 drives. Capable Oracle StorageTek drives include drives with the T10000C and T10000D format.- Enabling and disabling logical block protection
You can specify logical block protection for read and write operations, or only for write operations. You can also disable logical block protection if it is enabled. By default, logical block protection is disabled because of performance effects that result from CRC validation on the server and the tape drive. - Read/write operations to volumes with logical block protection
Read/write operations to empty or filling volumes depend on whether the volumes have logical block protection. Protected and unprotected data blocks cannot be mixed on the same volume. - Storage pool management
To mix protected and unprotected data in a library, you must create different device classes and different storage pools to separate the data. The device classes associated with the protected data can specify logical block protection for read/write operations or only for write operations.