CA Tape Encryption Installation and Configuration Best Practices › Configuration for Optimal Performance › Compression

Compression

Enable the CA Tape Encryption compression feature.

Business Value:

Enabling CA Tape Encryption compression and selecting the best compression method for your site reduces the number of tapes required for your business.

Additional Considerations:

The IDRC compression provided in most tape hardware is rendered ineffective by encryption. Tape files that used to fit on one tape cartridge might expand to a second or third cartridge. The built-in compression processing in CA Tape Encryption, includes:

• Nine software compression algorithms (S0-S8)
• Five hardware compression algorithms (H1-H5)
• A utility that evaluates the effectiveness of the different compression algorithms on your data

To activate compression, specify the Compress= parameter in either the Dynamic Options member or in specific symmetric key definitions. Use the MinimumCompressionRate = parameter to turn off compression if the desired rate of compression is not met.

Use the S0 compression algorithm if you do not have the time to research the best compression algorithm. S0 is a standard Run Length Encoding (RLE) algorithm primarily used for files that contain redundant alphanumeric data such as blanks, zeros, and asterisks. The S0 algorithm generally produces the best results with fewer CPU cycles.

If CPU resources are available, the S8 algorithm might result in better compression. The S8 algorithm is an adaptive Ziv-Lempel algorithm commonly referred to as LZ78, but the data is first compressed using the S0 method (RLE) to reduce the amount of data that must be processed by LZ78.