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Configuring zEnterprise Data Compression on z/OS (A Cheat Sheet)
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By Anthony Sofia, z/OS Software Development
Installing, configuring and verifying a zEDC Express installation is not a difficult task but it involves traversing a few different z/OS publications. This post will summarize each step and then provide references to the IBM publications which provide the details required. The first sections are related directly to bringing the zEDC Express devices online to z/OS with the final two sections dedicated to enabling exploiting programs to leverage the newly installed zEDC Express devices.
Defining the device
The first configuration step is defining a zEDC Express function to z/OS with an IODF update. The z/OS HCD User’s Guide provides information on working with zEDC Express adapters in the Working with PCIe Function chapter.
Enabling the Priced Software Feature
The zEDC Express software support is a priced feature of z/OS. This requires changing the IFAPRDxx PARMLIB member to include the following statement:
PRODUCT OWNER('IBM CORP')
Once the member is updated an IPL will be required for the zEDC Express device driver to recognize the enablement.
Additional information about the IFAPRDxx PARMLIB member can be found in the z/OS MVS Initialization and Tuning Reference under the chapter IFAPRDxx (Product Enablement Policy).
Viewing the device in z/OS
Once the device is defined the next step is to make sure z/OS has access to it. The z/OS MVS System Commands manual provides information on the D PCIE command in the chapter Displaying PCIE Information.
Even if someone is not writing code to use the zEDC Express directly there is valuable overview information in the z/OS MVS Callable Service for HLL manual. This describes the function of the card as well as a central space for software requirements.
Setting up z/OS SMF
With devices online the z/OS System Management Facilities (SMF) can be used to compress the data that is being written to an SMF logstream. A new option COMPRESS can be added to either the LSNAME, DEFAULTLSNAME or globally in the SMFPRMxx PARMLIB member. There is also another option, PERMFIX, which allows the installation to dictate how much of the SMF buffer pool is permanently page fixed for zEDC Express support per logstream.
The IFASMFDL program now has an option to force zEDC Express to be used when uncompressing the data as it is retrieved from an SMF logstream. The alternate is to allow IFASMFDL to fall back to a software based decompression which would perform far worse than the zEDC Express.
For additional information see the z/OS MVS System Management Facilities (SMF) manual.
Enabling zlib Applications
There are two places to look for zlib configuration information. The first is (again) the z/OS MVS Callable Service for HLL manual. This includes information on setting up SAF authorizations for calling programs and the requirements related to using effective buffer sizes.
There is a new PARMLIB member, IQPPRMxx, which can be used to control some of the behavior of zlib at a system level. The details of this new PARMLIB member are in the z/OS MVS Initialization and Tuning Reference in chapter IQPPRMxx (PCIE Related Parameters).
For additional questions one can check the zEnterprise Data Compression (zEDC) Express FAQ which contains a breadth of information with respect to pricing, interaction and future support.
Anthony Sofia is a Software Engineer in the System z development organization in Poughkeepsie and was the development lead for the z Enterprise Data Compression software support. Anthony has worked in System Z development for 10 years and has experience in several areas of z/OS and System z.