Review PFA check values

Description

Before z/OS V2R2, Predictive Failure Analysis (PFA) defined the following default values for the checks listed:
  • TRACKEDMIN(3) for PFA_SMF_ARRIVAL_RATE and PFA_MESSAGE_ARRIVAL_RATE.
  • STDDEVLOW(4) in PFA_ENQUEUE_REQUEST_RATE.
In z/OS V2R2, changes were made to the algorithm that PFA uses, and to the default PFA check values, to work more accurately with the algorithm changes. The changes are intended to accomplish the following goals:
  • Increase the accuracy of the PFA checks
  • Reduce false positives while still issuing valid exceptions.
  • Choose which address spaces to track more accurately.

Table 1 provides more details about this migration action. Use this information to plan your changes to the system.

Table 1. Information about this migration action
Element or feature: BCP.
When change was introduced: z/OS V2R2.
Applies to migration from: z/OS V2R1 and z/OS V1R13
Timing: Before the first IPL of z/OS V2R2.
Is the migration action required? Yes, if you are using PFA and not satisfied with the results.
Target system hardware requirements: None.
Target system software requirements: None.
Other system (coexistence or fallback) requirements: None.
Restrictions: None.
System impacts: None.
Related IBM® Health Checker for z/OS® check: None.

Steps to take

Follow these steps:
  1. Determine whether you are using a HZSPRMxx parmlib member that contains one or more of the following checks, or if you manually change the parameters for these PFA checks by using the MODIFY command supplied by IBM Health Checker for z/OS:
    • PFA_ENQUEUE_REQUEST_RATE
    • PFA_SMF_ARRIVAL_RATE
    • PFA_MESSAGE_ARRIVAL_RATE.
  2. If you are changing values for any or all of the checks, determine whether the following parameters are being set for the checks in your HZSPRMxx parmlib member, and if the value set is anything other than the following value:
    • PFA_ENQUEUE_REQUEST_RATE: STDDEVLOW(8)
    • PFA_MESSAGE_ARRIVAL_RATE: TRACKEDMIN(2)
    • PFA_SMF_ARRIVAL_RATE: TRACKEDMIN(2)
  3. If yes, remove the change to those values from the HZSPRMxx parmlib member. Do not change them using the MODIFY command.
  4. Restart PFA to begin by using the new default values.
  5. After PFA runs for more than a week, if the current default values are not sufficient for your installation, consider changing them based on the results from that period.

Reference information

For more information about the checks, see z/OS V2R2 Problem Management.

Parent topic: BCP actions to perform before the first IPL of z/OS V2R2