PM81046: Write-behind loaders in multimaster replication (MMR) domains produce LoaderException and KeyNotFoundException exceptions.

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APAR status

  • Closed as program error.

Error description

  • Under some conditions, when a WebSphere eXtreme Scale domain
    is replicating with MMR to a second WebSphere eXtreme Scale
    domain, and each domain is using a write-behind loader
    configuration, errors might occur.
    
    If the domains are processing many short transactions to the
    same set of keys, one or both domains might receive
    intermittent LoaderException conditions. For example,
    a LoaderException with a KeyNotFoundException might cause a
    "Delete over delete is not allowed" exception message.
    
    The failed operation is inserted into the write-behind loader,
    but is not updated in the map, and the application is required
    to take action either by re-applying update operations or by
    repeating delete operations.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:  WebSphere eXtreme Scale users who run       *
    *                  multimaster replication (MMR) scenarios     *
    *                  with a write-behind loader configuration.   *
    ****************************************************************
    * PROBLEM DESCRIPTION: Linked MMR domains can receive          *
    *                      spurious LoaderException and            *
    *                      KeyNotFoundException exceptions.        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    Due to expected timing effects, linked MMR domains running many
    small transactions on the same set of keys can cause
    the transactions to be applied out of order. The write-behind
    loader determines that the misplaced application of
    transactions causes an error scenario and fails to apply the
    transactions.
    

Problem conclusion

  • The write-behind loader now processes the transactions in the
    correct order, rather than applying erroneous transactions out
    of order.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PM81046

  • Reported component name

    WS EXTREME SCAL

  • Reported component ID

    5724X6702

  • Reported release

    860

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-01-21

  • Closed date

    2013-06-17

  • Last modified date

    2013-06-17

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

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

Fix information

  • Fixed component name

    WS EXTREME SCAL

  • Fixed component ID

    5724X6702

Applicable component levels

  • R860 PSY

       UP



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Document information


More support for:

WebSphere eXtreme Scale

Software version:

860

Reference #:

PM81046

Modified date:

2013-06-17

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