102903 HIPER MCLs for 2084

• Document number:

  102903

• Machine type:

  2084

• Models affected:

  ALL MODELS

• Abstract:

  Consolidated HIPER MCL Alerts

Description

HIPER MCLs 066 and 067 in the J12558 (i390/ML) stream were released to RETAIN to address an issue which can occur when a 2084 is connected to a 9037-2 sysplex timer. The following 2084 SRCs are symptomatic of this issue:
SRC 20320118 - ETR "switch to local" event (followed by an almost immediate "switch to ETR" event) and/or,
SRC 2032010F - ETR "sync check" event
These events are more likely to occur when an ETS (External Time Source) connection is done and, as a result, the 9037-2 needs to steer its clock to track to the External Time Source.

While these SRC events are likely to be transparent to the operation of z/OS images running on the 2084 which reports these SRCs, a sympathetic effect has been observed in the following configuration:
z/OS image(s) are running on a different physical system than the 2084 which reports these SRCs and these z/OS image(s) are connected to a CF image running on the 2084 which reports these SRCs
The sympathetic effect is a potential temporary loss of one or more coupling links from the z/OS image(s) to the 2084 CF image or a disabled WAIT0A2 on the z/OS images.

The HIPER MCLs should be installed on all 2084 systems which connect to a 9037-2 Sysplex Timer and even more urgently, on systems which match the above configuration. These MCLs can be installed and activated non-disruptively. (See "Special Installation Considerations" section.)

HIPER MCL 069 in the J12558 (i390/ML) stream was released to RETAIN to address an issue which can surface as increased CPU utilization. The condition will surface after the installation of concurrent MCLs in the J12558 (i390/ML) stream or when some CP hardware recovery event occurs. Once triggered, the condition will persist until an IML is performed or when HIPER MCL 069 in the J12558 stream is installed. The magnitude of the impact is related to the number of processors in a partition and the rate of I/O interrupts being processed by that partiiton. If the condition exists on a machine, it is cleared when the MCL is installed non-disruptively. (See "Special Installation Considerations" section.) If your machine encounters this condition, then the impact would usually be in the range of several percent, with the possibility of higher values for large partitions handling high rates of I/O interrupts.


HIPER MCL 054 in the J12558 (i390/ML) stream was released to RETAIN to address an issue during channel resets which can set the system up for a subsequent system checkstop during steady state system operation. SRCs 2232A000, 229C0202, and 22410222 are associated with this error. The MCL was released to RETAIN on September 3, 2003. The MCL can be installed non-disruptively. (See "Special Installation Considerations" section.) However, an IML is required to activate the fix.

IBM recommends that these HIPER MCLs be installed as soon as possible.
Special Installation Considerations
Several accounts have observed z/OS message IXL160E ("CF Request Time Ordering: Required and not-enabled; Reason: Request Time Ordering Function Failure") when MCLs in the J12558 (i390/ML) stream are installed non-disruptively. When this message appears, z/OS image(s) lose connectivity with CF image(s). This could potentially result in lost z/OS images (GRS wait state) or application failures due to the loss of "data sharing".

Since this issue only occurs in specific configurations, the exposure can be avoided by following these recommendations.

If the z/OS image(s) on the 2084 are not connected to a CF partition on either a 2084 or a 2064-2xx (Turbo), the exposure does not exist and the MCLs can be installed non-disruptively.

If the z/OS image(s) on the 2084 are connected to a CF partition on either a 2084 or a 2064-2xx (Turbo). then one of the following options should be used when installing MCLs.
Take down all z/OS images on the 2084 which are connected to a CF partition on either a 2084 or a 2064-2xx (Turbo) and install the MCLs non-disruptively; or
Move the structures from the CF image(s) to one or more CF images which are not on a 2084 or 2064-2xx (Turbo) system and then install the 2084 MCLs non-disruptively. Upon completion of the MCL session, the structures can be moved back to the CF images on the 2084 or 2064-2xx (Turbo) machines; or
Install the 2084 MCLs disruptively.
Note: These MCL install instructions need to be followed until MCL083 in the J12558 (i390/ML) stream
is finally installed / activated. This MCL is targeted to be released on Friday, October 31, 2003 as part
of the 2084 GA2 support MCLs.

Recommended Action

IBM recommends that these HIPER MCLs be installed as soon as possible.

If you have any questions, please contact your service provider.