I am exploring available methods for access to new SMF data. MVS exits
IEFU83, IEFU84 and IEFU85 historically provide access depending on the call
type and environment. Writing a new exit interface, I'd clearly use the newer
IEFU86 exit as it handles all three conditions provided by IEFU83, IEFU84 and
IEFU85 along with supporting extended SMF record types greater than 255
Naturally there are inherent risks with working within MVS exit points.
IFASEXIT is under consideration as I can use DYNALLOC to provide for the
SUBSYS interface text unit(s) and read log stream based SMF data in that
fashion. If configured properly, this could allow access to all CF based SMF
log stream data for the sysplex.
As observed with IFASMFDL and IFASEXIT, IXGCONN and IXGBRWSE are also
documented SMF interfaces. The sysplex services are documented in the
Authorized Assembler Services References and Guide (IXGCONN and IXGBRWSE).
What isn't documented well is the format of the log block data. From research
and looking at the involved CECs it appears the SMF log blocks are compressed
using the abilities of the z/EDC hardware compression card. What I'm looking
for is a better understanding of the compression used on the SMF data and an
example of how one might decompress that data on the fly as log blocks are
processed out of the log streams.
I was wondering if you could expand on the method used to compress the data
(we have COMPRESS defined on both the DEFAULTLSNAME and LSNAME parameters in
SMFPRMxx) and, most importantly, how best to decompress the data stored in the
log blocks.
Looking forward to your response given you are part of the IBM SMF level 3
team.
Regards,
Stan
-----Original Message-----
From: IBM Mainframe Discussion List <[email protected]> On Behalf Of
Bonnie Ordonez
Sent: Monday, April 15, 2019 3:12 PM
To: [email protected]
Subject: Re: SMF Log Blocks
You can use either of the following interfaces to extract data from the SMF log
stream:
IFASMFDL, which is the SMF dump utility
IFASEXIT, which is the SMF Logstream Subsystem Exit
These are the intended interfaces. They return SMF data in the form of SMF
records rather than the entire log block of information. They are documented
in the SMF manual.
Bonnie Ordonez, IBM, SMF Level 3
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