Managing Operations › Processing Restrictions

Processing Restrictions

The following restrictions apply to CA Tape Encryption processing:

• CA Tape Encryption only supports Standard Label (SL) tapes. Encryption or decryption capabilities are not provided for non-SL tapes.
• Applications using the z/OS Checkpoint Restart facility are not supported.
• CA Tape Encryption:
  • Dynamically converts SL tape volumes to SUL volumes. The label change is masked from the application. To the application, the tape appears to be SL.
  • Updates the HDR1 record and inserts User Header Labels and User Trailer Labels with encryption processing information. Header and trailer labels are installed through a DCB exit (DCBX) that is dynamically added by CA Tape Encryption.

    Important! Any programs or utilities that dynamically modify the DCB exit list must be tested with CA Tape Encryption to help ensure that there are no incompatibilities.

• The Multiplatform Decryption Utility (MDU), which your non-z/OS business partners use to decrypt data encrypted by CA Tape Encryption, only supports the decryption of standard fixed or fixed-blocked datasets.
• CA View modifies the HDR1 after tape open processing by rewinding the tape and rewriting the HDR1. You must obtain a compatibility PTF for Unicenter CA View to work correctly with CA Tape Encryption. Failure to obtain the required maintenance may result in creating tapes with encrypted data that are not recognized by CA Tape Encryption as encrypted tapes; consequently CA Tape Encryption would not decrypt these types of tapes.
• CA Tape Encryption allows you to select the data sets you want to encrypt. For many mainframe applications, tape is the primary medium. A tape data set may be the first and only copy of your business critical data, as opposed to a backup of such data. If you plan to encrypt a primary data set when it is being written to tape, you should thoroughly test your application's encryption and decryption processing to help ensure that there are no possible incompatibilities with CA Tape Encryption.
• Data blocks smaller than 16 bytes are not supported by CA Tape Encryption.
• DISP=OLD / DISP=SHR Restrictions. When DISP=OLD or DISP=SHR is specified and the tape is being opened for output, CA Tape Encryption prevents a job from rewriting a data set in unencrypted mode. CA Tape Encryption ABENDs a job performing RECREATE processing to prevent a previously encrypted data set from being overwritten.

Note: In tape management systems, this is referred to as RECREATE processing. RECREATE processing is defined as the attempt to rewrite the same data set to the same volume serial number and file sequence number.