IBM eServer zSeries 990 Technical Guide

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

when

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.