IBM Support

IT40074: MISSING READ-AHEAD IN RSS UNDERGOING LOGICAL LOG RESTORE

Subscribe to this APAR

By subscribing, you receive periodic emails alerting you to the status of the APAR, along with a link to the fix after it becomes available. You can track this item individually or track all items by product.

Notify me when this APAR changes.

Notify me when an APAR for this component changes.

 

APAR status

  • Closed as program error.

Error description

  • An RSS having to receive logical logs from log restore rather
    than from primary might perform poorly due to missing
    read-ahead.
    
    Reason is an RSS read-ahead optimization moving the read-ahead
    from bld_logrecs thread to RSS_Recv thread which, during log
    restore, is in wait state, so would not see any log records and
    not submit any read-ahead requests.
    
    You can verify non-existing read-ahead be 'onstat -g rah'
    returning empty read-ahead statistics.
    

Local fix

  • Workaround, for the duration of the log restore:
    
     onmode -wf CDR_FEATURES NORAOPT
    
    After log restore completed, when logs are being received from
    primary, re-enable the optimization using
    
     onmode -wf CDR_FEATURES RAOPT
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * Users of Informix Server prior to 14.10.xC8.                 *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to Informix Server 14.10.xC8.                        *
    ****************************************************************
    

Problem conclusion

  • Fixed in Informix Server 14.10.xC8.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT40074

  • Reported component name

    INFORMIX SERVER

  • Reported component ID

    5725A3900

  • Reported release

    E10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2022-02-25

  • Closed date

    2022-04-08

  • Last modified date

    2022-04-08

  • 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

    INFORMIX SERVER

  • Fixed component ID

    5725A3900

Applicable component levels

[{"Line of Business":{"code":"LOB10","label":"Data and AI"},"Business Unit":{"code":"BU053","label":"Cloud \u0026 Data Platform"},"Product":{"code":"SSGU8G","label":"Informix Servers"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"E10"}]

Document Information

Modified date:
09 April 2022