OMCS Hardware Compression Feature (FMID ASEB201)

Hardware Compression Feature makes use of S/390 hardware compression to significantly reduce the CPU cost of using OMCS compression options.

Hardware Compression Feature is a separately-licenced extra-cost option for OMCS licensees.

OMCS database compression

In November 1990 ASE introduced software compression of OMCS database files. Controlled by setting the "Sysout Dataset Construction Method" variable (JPVASDCM) to "C" in OMCS Job Processing Rules, software compression has been extensively used by many sites to improve disk and cartridge utilisation. Disk space savings of 75% or more are usual for report files. Backup and restore times are also reduced. The unit of compression, and hence decompression, is the database block, so that when users browse or view a section of a large database file only the relevant blocks need be decompressed.

The cost of achieving such agressive compression is increased CPU consumption. In response to customer requests ASE made the Hardware Compression Feature available as an RPQ to specific licensees from November 1997.

Six months in development, the Hardware Compress Feature monitors its own efficiency, adapting its compression dictionary to the nature of the data stream as necessary to achieve high overall efficiency. Compressed file sizes are typically a little smaller than those produced by software compression.

Quoting ASE Technical Bulletin TB97-0001 on the CPU savings possible with the Hardware Compression Feature:

• "From the table it can be seen that hardware compression produces the same size or smaller output file while using 25% less CPU time. Hardware decompression uses 75% less CPU time than software decompression. As a single file may be accessed and decompressed many times per day, hardware decompression will reduce the CPU usage significantly."

Licensing issues

You must be explicitly licensed to download and install FMID ASEB201.

Please contact ASE to enquire about licensing issues for Hardware Compression Feature.

Last Updated:02:05 TUE 8th May 2001 GMT