Compression enablement for disk image copies (COMPRESS)

COMPRESS=YES specifies the compression of disk image copies unless it is overridden at runtime by the COMPRESS syntax option.

See COMPRESS, COPY-IMAGECOPY-syntax-options, and OPTIONS-syntax-option-description for more information about the COMPRESS option used with the COPY, COPY IMAGECOPY, and OPTIONS commands, respectively. The installation option default is COMPRESS=NO, which specifies no disk compression. COMPRESS=YES requests compression using the BMC Extended Compression Architecture (XCA) technology through the PACLOG utility.

To enable compression, the PACLOG load library must be in the BMC AMI Copy STEPLIB or JOBLIB. For more details, seePACLOG for DB2 documentation .

The following table provides typical performance data that compares elapsed time, CPU time, and disk usage for the following BMC AMI Copy runs creating a full copy of 15,280 pages:

• An BMC AMI Copy run using COMPRESS=YES
• An BMC AMI Copy run using COMPRESS=NO

Performance statistics for the COMPRESS option

^{1 Change percentages are relative to the BMC AMI Copy run with COMPRESS=NO.}

In practice, variances in elapsed time might occur, depending on CPU and channel availability. On a system with a busy CPU, the increase in CPU time might increase elapsed time.