Using CA Tape Encryption in Your z/OS Environment › Integrated Compression for Symmetric Key Encryption › Compression Threshold › How Compression Threshold Monitoring Works

How Compression Threshold Monitoring Works

Because compression uses processor resources, it is useful to check to see if you are getting the benefits of the overhead that compression requires. The compression threshold feature periodically monitors compression activity to determine if compression is effective or not effective. The following points outline this process:

• The compression rate is checked after the first 24 MB and then after every 8 MB are written to tape to see if the compression threshold continues to be met.
• If the compression threshold is not met, then the next 80 MB of data is processed without attempting compression. At this point a buffer of data is compressed and the threshold checked. This is repeated until the threshold is met or the end of the file or end of volume.
• If the threshold is met, then compression continues with a threshold check every 8 MB.
• If end of volume, the process will start over with bullet one on the new volume.