Determining the function level of an IRLM group in coexistence

IRLM communicates coexistence information by using function levels. A function level is an ever-increasing number that each IRLM can use to tell other IRLMs in the group what level of function it supports.

About this task

The group function level is the minimum of the individual IRLM function levels for all IRLMs that can coexist. An IRLM that tries to join a data sharing group is prevented from doing so by active members that cannot coexist with the new IRLM's function level.

When the function level for the group changes, that change is serialized by IRLM with lock structure rebuilds. In most cases, however, the lock structure does not actually do a full rebuild. The first phase of the rebuild is enough to quiesce the work and cause the function level change to occur. These partial rebuilds take place when an IRLM joins the group and if that activity causes the group function level to change. For example, if the IRLM group is currently at function level n, and the IRLM member that wants to join the group is at n-1, the partial rebuild occurs to lower the group function level.

Procedure

To determine IRLM function levels:

Enter the following command:
Begin general-use programming interface information.
MODIFY irlmproc,STATUS,ALLI
End general-use programming interface information.

Example

Assume that a data sharing group has three members running Db2 13 at function level V13R1M100, and one member running Db2 12. Issuing the MODIFY irlmproc,STATUS,ALLI command from one of the three Db2 13 members produces output that is similar to the following output:

Begin general-use programming interface information.

DXR103I QR21002 STATUS 622                                             
        IRLMS PARTICIPATING IN DATA SHARING GROUP FUNCTION LEVEL=3.040 
        IRLM_NAME IRLMID STATUS LEVEL SERVICE MIN_LEVEL MIN_SERVICE    
          PR21*    001     UP   3.050 PH43770   1.022     PM28625      
          QR21     002     UP   3.040 PM28625   1.022     PM28625      
          SRLM     004     UP   3.050 PH43770   1.022     PM28625      
          TRLM     005     UP   3.050 PH43770   1.022     PM28625      
    DXR103I End of display

End general-use programming interface information.

The IRLMs in the preceding example are at group function level 3.040, which is the lowest level of any of the individual members (QR21). The MIN_LEVEL field shows the minimum level with which this IRLM can coexist. MIN_SERVICE indicates the service or release that corresponds with that MIN_LEVEL.