The term Block Padding is used in backup to tape environments when there is a need for tape copy and backup mirroring. Tape still remains a sequential medium, using different tracks to store data. Therefore, there are slight variations in the overall capacity of individual tapes. This can pose a significant challenge when attempting to make an exact copy from a tape which is slightly larger than the destination tape. Planning for this eventual issue must be done before the initial tape initialization.
HP Data Protector uses a parameter called “OB2BLKPADDING” in the omnirc file on each system (media agent) connected with a tape device. The parameters’ value defines the number of empty blocks to be added on the specific tape. This empty space allows tape content to be copied to another tape of the same type without any problem as the empty space is not copied from the source.