IBM Support

VM66724: INCREASE CMS TAPE BLOCK SIZE

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

  • Increase the block size supported for native CMS tape I/O from
    64KB to approximately 1MB.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: Users of products or applicatons that        *
    *                 exploit native CMS tape I/O functions        *
    *                 (RDTAPE and WRTAPE)                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    ****************************************************************
    * RECOMMENDATION: APPLY PTF                                    *
    ****************************************************************
    The native CMS tape support block size limit is increased from
    64K to roughly 1M. This enables applications and products such
    as backup solutions that exploit the native interfaces to use
    larger blocks, which can improve their performance.
    

Problem conclusion

Temporary fix

  • FOR RELEASE ES-CMS-730-BASE :
    PREREQ: NONE
    CO-REQ: NONE
    IF-REQ: NONE
    

Comments

  • Tape channel programs are now constructed using multiple
    data-chained CCWs to accommodate a larger block size.
    The maximum tape blocksize supported is available in a new field
    in NUCON, MAXTAPBS. In CMS releases without this support, this
    field is zero, indicating that the maximum block size is 65,535.
    The RDTAPE macro no longer limits a numeric buffer length to
    65,535 bytes. The associated MNOTE is no longer produced and the
    buffer length is not changed. The length is still checked at run
    time and will produce return code 1 if it exceeds the supported
    maximum.
    

APAR Information

  • APAR number

    VM66724

  • Reported component name

    VM CMS

  • Reported component ID

    568411201

  • Reported release

    730

  • Status

    CLOSED UR1

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    YesSpecatt / New Function / Xsystem

  • Submitted date

    2023-10-09

  • Closed date

    2023-11-10

  • Last modified date

    2024-04-04

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

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

    UM90377

Modules/Macros

  • DMSNUC   DMSTIO   DMSTLB   DMSTLW   DMSZNUC  NUCON    NUCONP
    NUCONPZ  NUCONZ   RDTAPE   WRTAPE
    

Publications Referenced
SC24626273    

Fix information

  • Fixed component name

    VM CMS

  • Fixed component ID

    568411201

Applicable component levels

  • R730 PSY UM90377

       UP23/11/14 P 2401  

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.

[{"Business Unit":{"code":"BU011","label":"Systems - zSystems software"},"Product":{"code":"SG27M"},"Platform":[{"code":"PF054","label":"z Systems"}],"Version":"730"}]

Document Information

Modified date:
04 April 2024