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

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 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