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VM66112: CANT READ LABEL ON FLASH COPY TARGET AFTER MINIDISK CONSOLIDATION

A fix is available

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APAR status

  • Closed as program error.

Error description

  • Problem with CP FLASHCOPY moving multiple fullpack minidisks to
    a single larger real volume.  Unable to read label on minidisks
    once relocated to target real device.   This occurs on any
    minidisk moved to a target offset other than real cylinder 0.
    CP FLASHCOPY usage note indicates that mixing of non-FP & FP
    minidisks is not supported.   However, it would be great to get
    this working.   It is a valuable use case and considered a
    defect here.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All users of z/VM FLASHCOPY are affected     *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    ****************************************************************
    * RECOMMENDATION: APPLY PTF                                    *
    ****************************************************************
    The external symptom of the problem is that when fullpack
    minidisks are consolidated onto a larger volume, their
    data tracks and data records may not be able to be accessed,
    as when a process goes to obtain one of said tracks or
    records, they will not be addressed correctly due to an
    oversight in CP FLASHCOPY.
    
    The problem can be recreated by using CP FLASHCOPY to
    consolidate multiple fullpack minidisks onto a larger volume.
    Once this has been done, attempt to access a data record on
    any of the cylinders that isn't on the first minidisk in this
    volume. This will result in an incorrect record being
    accessed or a 'record not found' error.
    
    This fault is due to the way that flashcopy addresses the
    minidisks when it transfers them over. In every case, record
    zero on each data track will contain the cylinder number
    relative to the entire storage device to which the minidisks
    have been transferred. Before this fix, all of the data
    records were addressed this way due to flashcopy, but with
    the fix, the remaining data records are addressed relative to
    the minidisk to which they belong.
    
    Example:
    On the new storage device, we have the 3340th cylinder, which
    is referenced as such in every data record in every data track
    contained within the cylinder.
    
    Each minidisk has 3339 cylinders, so this is the 1st cylinder
    on the 2nd minidisk. Code that used to refer to said cylinder
    cannot find it, because every record says it is on cylinder
    3340, and this code is searching for cylinder 1. The true
    cylinder number (3340) is only recorded on data record 0 of
    each data track after the fix.
    

Problem conclusion

  • Module HCPNFC was updated to turn on the 'force relocation'
    bit when the failing use case is recognized. The use case is
    when multiple fullpack minidisks are consolidated onto a
    single larger real volume.
    
    Also, updated the VM FLASHCOPY VDEV command description in
    the CP COMMAND AND UTILITIES REFERENCE to note that a
    fullpack minidisk may be copied to a non-fullpack minidisk
    for the purpose of storage consolidation. This was reflected
    in usage note 4.
    

Temporary fix

  • FOR RELEASE VM/ESA CP/ESA R640 :
    PREREQ: VM66029 VM66153
    CO-REQ: NONE
    IF-REQ: NONE
    FOR RELEASE VM/ESA CP/ESA R710 :
    PREREQ: NONE
    CO-REQ: NONE
    IF-REQ: NONE
    

Comments

APAR Information

  • APAR number

    VM66112

  • Reported component name

    VM CP

  • Reported component ID

    568411202

  • Reported release

    640

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-01-02

  • Closed date

    2018-11-09

  • Last modified date

    2019-03-22

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

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

    UM35390 UM35391

Modules/Macros

  • FLASHCOP HCPNFC   VDEV
    

Publications Referenced
SC24617513SC24626810   

Fix information

  • Fixed component name

    VM CP

  • Fixed component ID

    568411202

Applicable component levels

  • R640 PSY UM35390

       UP18/11/22 I 1000

  • R710 PSY UM35391

       UP18/11/22 P 1901

Fix is available

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Document Information

Modified date:
22 March 2019