Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• WLM routing services give recommendations which cause routers to
  send to much work to certain systems.  These situations are
  found on LPAR systems, very often with a load of around 95% and
  more than one logical processor assigned to the LPAR.
  The summed free capacity values across all LPARS contains in
  this case a value which is much higher than the available CEC
  capacity.  This incorrect calculation of free capacity results
  in WLM making bad recommendations.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of z/OS 1.4 (HBB7707) and          *
  *                 above.                                       *
  ****************************************************************
  * PROBLEM DESCRIPTION: WLM routing services provide            *
  *                      recommendations which cause routers to  *
  *                      send to much work to certain systems.   *
  *                      The problem occurs in an LPAR           *
  *                      environment, very often with a load of  *
  *                      around 95% and more than one logical    *
  *                      processor assigned to the LPAR.  The    *
  *                      problem is more likely to occur when    *
  *                      the sysplex consists of multiple LPARs  *
  *                      on different CECs. The summed free      *
  *                      capacity values across all LPARS        *
  *                      contains in this case a value which is  *
  *                      much higher than the available CEC      *
  *                      capacity. This incorrect calculation of *
  *                      free capacity results in WLM making bad *
  *                      routing recommendations and can result  *
  *                      in too much work being routed to a      *
  *                      highly utilized LPAR when another LPAR  *
  *                      on a different CEC in the sysplex has   *
  *                      more available capacity.                *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  WLM bases the free capacity value used in WLM routing services
  and for starting new initiators on the wait time of the logical
  processors (LCP) for the partition the system is running in. It
  is now possible that this wait time is higher than the total
  capacity of the CEC would suggest. As a result the sum of wait
  times for multiple partitions on the CEC show a higher available
  capacity than the real available capacity for the CEC. The
  reason is that the LCPs can be dispatched at different
  intervals. It is possible that a certain LCP is in a wait for a
  longer period of time while the other LCPs are relative busy. As
  a result the total wait time of all LCPs may look too high.
  This can result in too much work being routed to a highly
  utilized system in a sysplex environment although another system
  on a different CEC in the sysplex has more available capacity.
  

Problem conclusion

• The free capacity calculation in module IRAPAPCA considers now
  in addition to the wait time of the LCP(s)
  - the guaranteed free LPAR capacity,
  which is the weight related portion of the total CEC capacity
  minus the used capacity for this partition,
  - the CEC related free LPAR capacity,
  which is the weight related portion of the free CEC capacity for
  this partition.
  - the configuration related free LPAR capacity,
  which is maximum partition capacity possible defined by the
  number of configured LCPs minus the used LPAR capacity.
  
  Rules:
  1. The LCP wait time related free capacity value is used, if
     - Below 90% CEC utilization, or
     - Wait completion = YES, or
     - Dedicated LCPs are assigned to this LPAR, or
     - System is running as a VM guest, or
     - The LCP wait time related free capacity value is less or
       equal to the Guaranteed free LPAR capacity or is less or
       equal to the CEC related free LPAR capacity
  2. The Guaranteed free LPAR capacity value will be used, if
     - None of the previous is true, and
     - Initial capping is not active and Soft capping is not
       active and the Guaranteed free LPAR capacity value is less
       than the LCP config free LPAR capacity, and
     - the Guaranteed free LPAR capacity value is greater than the
       CEC related free LPAR capacity value, or
     - Initial capping was specified for this LPAR and the
       Guaranteed free LPAR capacity value is less than the LCP
       config free LPAR capacity, or
     - Soft capping is active, and the Guaranteed free LPAR
       capacity value is less than the LCP config free LPAR
       capacity.
  3. The CEC related free LPAR capacity value will be used, if
     - None of the previous is true, and
     - no soft capping active and no initial capping active, and
       the Guaranteed free LPAR capacity value is less than the
       CEC related free LPAR capacity value, and the CEC related
       free LPAR capacity value is less than the LCP config free
       LPAR capacity.
  4. The LCP config free LPAR capacity value will be used, if
     - None of the previous is true.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UA20504 UA20505 UA20506 UA20507

Modules/Macros

• IEAVNP10 IRAD204  IRAEVSSI IRAILST  IRALCCT
  IRAMSBLD IRAMSCSH IRAPALCD IRAPAPCA IRAPASMF IRAPASM2 IRAPASS1
  IRAPASS2 IRAPASS3 IRAPASS4 IRAPASS5 IRAPASS6 IRAPASS7 IRAPASS8
  IRAPAS2D IRARMER3 IRARMSMF IRASASMF IRASMF99 IWMC4SMF
  

Fix information

• Fixed component name

  WORK LOAD MANAG

• Fixed component ID

  5752SCWLM

Applicable component levels

• R707 PSY UA20504

     UP05/08/24 P F508

• R708 PSY UA20505

     UP05/08/24 P F508

• R709 PSY UA20506

     UP05/08/24 P F508

• R717 PSY UA20507

     UP05/08/24 P F508

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.

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Product categories:

Software

Operating System

z/OS family

APARs - z/OS environment

Operating system(s):

MVS, z/OS

Software version:

709

Reference #:

OA10006

IBM Group:

IBM Server Group

Modified date:

2005-09-13