Chapter 6. Software support 141
Initial Command Response time for the device. A similar change has also been made to the
RMF Monitor II Device Activity recording in the SMF 79, subtype 9 records.
The SMF records for the SRM Decisions data stored in type 99 (subtypes 8 and 9) have also
been extended. These records now contain the LCSS ID for the WLM LPAR management
and I/O subsystem information.
6.2.6 RMF support
There are several changes to RMF reports to accommodate the enhanced I/O subsystem
and improved collection of channel measurement data.
The I/O Activity report no longer shows the Control Unit Busy (CUB) and Director Port Busy
(DPB) times. (The corresponding percentage and pending reason fields for CUB and DPB
have also been removed from the Monitor III reports.) This information was already available
at an LCU level anyway and is much more useful than the figures being broken out for
individual devices.
Furthermore, the Director Port Busy field would only show a non-zero value for the events
all director ports were busy. If an individual director port was found to be busy, but a
connection was established through an alternate path, then this figure was not updated. With
FICON connections, a Director Port was never reported busy, since that type of channel
allows multiple data transfers to occur simultaneously.
A better measure of fabric contention has now been provided with the Initial Command
Response Time. This is a measure of the time taken from sending a command to a device, to
it responding that it has accepted the command. This new metric (AVG CMR DLY) has now
replaced the older AVG CUB and AVG DPB columns on the Monitor I Device Activity Report.
Corresponding DELAY CMR% and PENDING REASON CMR displays have been introduced
into the Monitor III reports. Monitor III exception reporting has also been updated to replace
the previous CUBDL and DPBDL conditions with the new condition CMRDL.
6.2.7 ICKDSF requirements
ICKDSF Release 17 is required on all systems that share DASD with a z990 processor.
ICKDSF 17 supports the new format of the CPU information field, which now contains a
two-digit LP identifier. ICKDSF uses the CPU information field instead of CCW
reserve/release for concurrent media maintenance. It prevents multiple systems from running
ICKDSF on the same volume, and at the same time allows user applications to run while
ICKDSF is processing. In order to prevent any possible data corruption, ICKDSF must be able
to determine all sharing systems that may potentially run ICKDSF; therefore, this support is
required for z990.
6.2.8 ICSF support
If you use z990 cryptographic hardware functions with ICSF, then you must install
Compatibility Support for this feature.
Important: The need for ICKDSF Release 17 applies even to systems that are not part of
the same sysplex, or that are running a non-MVS based operating system, such as z/VM.

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