Getting the Most out of zEDC Hardware Compression

Todd-Havekost

By Todd Havekost

One of the challenges our customers tell us they face with their existing SMF reporting is keeping up with emerging z/OS technologies. Whenever a new element is introduced in the z infrastructure, IBM adds raw instrumentation for it to SMF. This is of course very valuable, but the existing SMF reporting toolset, often a custom SAS-based program, subsequently needs to be enhanced to support these new SMF metrics in order to properly manage the new technology.

z Enterprise Data Compression (zEDC) is one of those emerging that is rapidly gaining traction with many of our customers, and for good reasons:

  • It is relatively straightforward and inexpensive to implement.
  • It can be leveraged by numerous widely used access methods and products.
  • It reduces disk storage requirements and I/O elapsed times by delivering good compression ratios.
  • The CPU cost is very minimal since almost all the processing is offloaded to the hardware.

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What Good is a zEDC Card?

BrettBy Dave Heggen

informatics inc: You Need Our Shrink!

The technologies involving compression have been looking for a home on z/OS for many years. There have been numerous implementations to perform compression, all with the desired goal of reducing the number of bits needed to store or transmit data. Hostbased implementations ultimately trade MIPS for MB. Outboard hardware implementations avoid this issue.

Examples of Compression Implementations

The first commercial product I remember was from Informatics, named Shrink, sold in the late 1970s and early 1980s. It used host cycles to perform compression, could generally get about a 2:1 reduction in file size and, in the case of the IMS product, worked through exits so programs didn’t require modification. Sharing data compressed in this manner required accessing the data with the same software that compressed the data to expand it.

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