IT36262: IBM MQ Appliance HA synchronization might be slow after restart of one of the appliances

APAR status

• Closed as program error.

Error description

• During a failover test, that included shutting down one of the
  high availability (HA) replicated appliances, slow
  synchronization times were experienced
  after the appliance came back online. In some of the tests, the
  appliances were able to sync in a matter of seconds but in some
  instances it took minutes.
  
  The following messages were noticed in the MQSystem logs when
  performing the tests.
  
  Working as expected:
  02/19/21 13:53:20 mqsystem mqrc 39372.1 AMQ3577I: HA
  replication to remote appliance 'APP01' for queue manager
  'HAQM1' using interface 'eth21' is available
  02/19/21 13:53:22 mqsystem mqrc 42923.1 AMQ3592E: HA status for
  queue manager HAQM1 is 'Inconsistent'
  02/19/21 13:53:22 mqsystem mqrc 43122.1 AMQ3598W: HA status for
  queue manager HAQM1 is 'Synchronization in progress'
  02/19/21 13:53:38 mqsystem mqrc 51859.1 AMQ3599I: HA status for
  queue manager HAQM1 is 'Normal'
  
  
  SLow sync times:
  02/19/21 15:56:55 mqsystem mqrc 38060.1 AMQ3577I: HA
  replication to remote appliance 'APP01' for queue manager
  'HAQM1' using interface 'eth30' is available
  02/19/21 15:56:57 mqsystem mqrc 42209.1 AMQ3592E: HA status for
  queue manager HAQM1 is 'Inconsistent'
  02/19/21 15:56:57 mqsystem mqrc 42412.1 AMQ3598W: HA status for
  queue manager HAQM1 is 'Synchronization in progress'
  02/19/21 16:05:56 mqsystem mqrc 85745.1 AMQ3599I: HA status for
  queue manager HAQM1 is 'Normal'
  
  The messages logs shows that sync speed was around 124K/sec.
  2021-02-19 15:31:26.052838-05:00 APP01 kernel: [ 2284.351928]
  drbd drbd_HAQM1/0 drbd7 APP02 Resync done (total 2197 sec;
  paused 0 sec; 124 K/sec)
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users using an IBM MQ Appliance HA configuration and restarting
  one of the appliances in the HA configuration
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  A defect in the drbd libraries used for HA replication caused
  slow synchronization.
  

Problem conclusion

• The IBM MQ Appliance firmware has been modified to update the
  drbd libraries to the version 9.0.28.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.1 LTS   9.1.0.8
  v9.2 LTS   9.2.0.3
  v9.x CD    9.2.3
  
  The latest available maintenance can be obtained from
  'WebSphere MQ Recommended Fixes'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
  
  If the maintenance level is not yet available information on
  its planned availability can be found in 'WebSphere MQ
  Planned Maintenance Release Dates'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
  ---------------------------------------------------------------
  

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

  MQ APPL M2002 V

• Fixed component ID

  5737H4701

Applicable component levels