Hardware-based BLC is available only on Teradata Database systems that include compression hardware. Hardware-based BLC creates little or no CPU resource contention with other database operations. Hardware-based block-level compression provides the same functions as software-based block-level compression.
Systems configured with BLC hardware also contain backup software that uses the same compression algorithm as the hardware. If the system is using hardware BLC and Teradata detects that the compression hardware is not functioning, the backup software automatically performs the compression.
To specify use of compression hardware, set the CompressionAlgorithm field in the DBS Control utility to ELZS-H.
Coexistence of Software BLC and Hardware BLC
Teradata Database lets data compressed with hardware compression and data compressed with software compression coexist simultaneously in the same table. This allows you to change easily from one method to the other.