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OA44207: NEW FUNCTION - SCALABILITY SUPPORT FOR SYSTEMS WITH UP TO 1TB OFREAL STORAGE

A fix is available

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You can track all active APARs for this component.

APAR status

  • Closed as new function.

Error description

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: Customers at HBB7730 and up, running with    *
    *                 large amounts of real storage, generally     *
    *                 between 256G to 1TB, or with a large         *
    *                 LFAREA, such as 256G.  A PTF will be         *
    *                 provided at HBB7790 only.                    *
    ****************************************************************
    * PROBLEM DESCRIPTION: This APAR provides new function to      *
    *                      address scalability issues for          *
    *                      customers running with large amounts    *
    *                      of real storage, generally between      *
    *                      256G to 1TB, or with a large LFAREA,    *
    *                      such as 256G.                           *
    *                                                              *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    This APAR provides new function to address scalability
    issues for customers running with large amounts of real
    storage, generally between 256G to 1TB, or with a large
    LFAREA, such as 256G.
    
    Without this APAR applied, the following issues may occur
    with large amounts of memory or with a large LFAREA:
    
    1. During system initialization, RSM must obtain disabled
       spin locks to initialize control structures. Running
       disabled can lead to spin loop time-outs and result in an
       ABEND071 which can lead to system failure.
    
    2. A large LFAREA (e.g., greater than 256G) requires a large
       amount of preferred real storage for PFTEs to represent
       the frames for the LFAREA.  During system initialization,
       obtaining these control structures may deplete preferred
       storage below the bar. One possible outcome is an
       XCF WAIT0A2.
    
    3. As the LFAREA size is increased, the amount of preferred
       storage above the bar is decreased. A lack of preferred
       storage can lead to a system hang or slowdown as
       requesters for this storage are indefinitely suspended.
    
    4. Processing requests for 4K frames from the LFAREA can
       lead to ABEND071 spin loop time-outs.
    
    5. A spin loop time-out ABEND071 may occur when a CONFIG
       STOR, OFFLINE command is processed for a large amount of
       real storage or with a large storage increment size, such
       as 1G or greater.
    
    6. A spin loop time-out ABEND071 may occur while scanning
       PFTEs during frame steal processing.
    

Problem conclusion

Temporary fix

Comments

  • This APAR provides new function to address RSM scalability
    issues with large amounts of real storage. The following
    describes the new function provided by this APAR:
    
    1. In the area of RSM initialization, the processing time
       while running disabled is reduced by initializing frames
       more efficiently.
    
    2. The area of real storage used to contain the PFTEs for
       the LFAREA is moved to a new area to help prevent the
       depletion of preferred storage below the bar.
    
    3. The size of the Pageable Large Area (PLAREA) is reduced
       to allow more preferred storage above the bar when the
       LFAREA is very large, generally above 70%. Also, RSM
       frame steal processing is enhanced to scan the PLAREA for
       4K frames to steal.
    
    4. New structures are defined for managing the LFAREA frames
       that are more efficient and will reduce the amount of
       time that RSM must run disabled to manage LFAREA frames.
    
    5. Processing for the CONFIG STOR, OFFLINE command has been
       enhanced to be more efficient to avoid a spin loop
       time-out ABEND071.
    
    6. RSM frame steal processing is enhanced to be more
       efficient in scanning the PFTEs by skipping over certain
       areas that are not eligible for steal processing.
    
    The following publications have been updated:
    
    z/OS MVS Initialization and Tuning Guide
    Document Number: SA23-1379
    Documentation updates for this publication are located in a
    pdf file, OA44207.pdf, available at:
    - http://publibz.boulder.ibm.com/zoslib/pdf/OA44207.pdf
    
    z/OS MVS Data Areas Volume 5
    Document Number: GA32-0939
    A new bit in the RCE is defined to indicate that this
    function is applied on this system.
    - In the section titled: RCE Cross Reference
       Name                 Hex Offset  Hex Value
    |  RCEOA44207APPLIED       14F         80
    
    - In the section titled: RCE Map
      Dec   Hex    Type/Value  Len  Name (Dim)  Description
      335   (14F)  CHARACTER    1   RCEFLAGS4   FLAGS
    |              1...  ....       RCEOA44207APPLIED
    |                                Indicates APAR OA44207
    |                                is applied on this system
    
    ×**** AE15/03/17 FIX IN ERROR. SEE APAR OA47316  FOR DESCRIPTION
    ×**** PE15/06/03 FIX IN ERROR. SEE APAR OA48001  FOR DESCRIPTION
    

APAR Information

  • APAR number

    OA44207

  • Reported component name

    RSM - REAL STOR

  • Reported component ID

    5752SC1CR

  • Reported release

    790

  • Status

    CLOSED UR1

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    YesSpecatt / New Function / Xsystem

  • Submitted date

    2014-01-08

  • Closed date

    2014-07-25

  • Last modified date

    2015-07-16

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

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

    OA44858 UA74198

Modules/Macros

  • IARMN    IARRCE   IAXBR    IAXGA    IAXGT
    IAXMH    IAXMI    IAXMP    IAXMR    IAXMT    IAXM8    IAXM9
    IAXQX    IAXRC    IAXRG    IAXRN    IAXSA    IAXSB    IAXSI
    IAXUA    IAXUC    IAXUM    IAXUN    IAXUO    IAXUZ    IAXVD
    IAXVH    IAXVS    IAXV2    IAXWB    IAXXG    IAXXI    IAXXR
    IAXYG    IAXYZ    IAXZVHVH IAXZVPFT IAXZVRIT IAXZXGCB
    

Publications Referenced
GA320939XX SA231379XX      

Fix information

  • Fixed component name

    RSM - REAL STOR

  • Fixed component ID

    5752SC1CR

Applicable component levels

  • R790 PSY UA74198

       UP14/07/30 P F407

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.



Document information

More support for: z/OS family

Software version: 790

Operating system(s): MVS, z/OS

Reference #: OA44207

Modified date: 16 July 2015