Data validation during read/write operations to tape

To validate data and identify data that is corrupted, you can use a feature that is called logical block protection. If you use logical block protection, IBM Spectrum® Protect inserts a cyclic redundancy check (CRC) value at the end of each logical block of data while it is written to tape.

With logical block protection, you can identify errors that occur when data is written to tape and during data transfer from the tape drive to IBM Spectrum Protect through the storage area network. Drives that support logical block protection validate data during read and write operations. The IBM Spectrum Protect server validates data during read operations.

If validation by the drive fails during write operations, the failure can indicate that data was corrupted during transfer to tape. In this case, the IBM Spectrum Protect server fails the write operation. You must restart the operation to continue. If validation by the drive fails during read operations, the failure can indicate that the tape media is corrupted. If validation by the IBM Spectrum Protect server fails during read operations, the failure can indicate that data was corrupted during transfer from the tape drive, and the server tries the operation again. If validation fails consistently, the IBM Spectrum Protect 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 IBM Spectrum Protect 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. When you specify CRC validation for a storage pool, data is validated only during volume auditing operations. Errors are identified after the data is written to tape.