PH23766: GDPS MGM REQUIRES UNIQUE SSID FOR ALL REPLICATION SITE LSS

APAR status

• Closed as documentation error.

Error description

• Although the GDPS Metro and GDPS Global - GM documentation
  explicitly states that use of disk subsystems with duplicate
  SSIDs is not supported, the GDPS Metro Global - GM Planning and
  Implementation Guide does not. Nonetheless, the requirement for
  uniqueness does exist, and failure to follow this configuration
  rule can cause GDPS to function incorrectly. One example of this
  is a planned suspension of the Global Mirror leg, which can
  cause an unplanned freeze of the Metro Mirror leg if both a
  Metro leg secondary SSID and a GM leg secondary SSID are the
  same.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * GDPS Metro Global - GM                                       *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * Missing documentation for GDPS MGM requirement for unique    *
  * SSIDs                                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  

Problem conclusion

• The GDPS Metro Global - GM Planning and Implementation Guide
  (ZG24-6758) needs to be updated. In section 2.2 "Disk subsystem
  planning", add a new "Disk naming and device numbering
  conventions" subsection, with the following text:
  
  Good naming conventions for logical subsystem numbers (LSS),
  disk subsystem IDs (SSIDs) and a good device numbering scheme
  can greatly simplify GDPS definitions and the management and
  operation of your MGM configuration. Use unique ranges that
  allow you to readily identify the associated Region and
  Replication Site.
  
  Restriction: The use of disk subsystems with duplicate SSIDs is
  not supported. They must be unique across all Regions and
  Replication Sites.
  

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

Applicable component levels