IRLM does not automatically rebuild if the number of members
decreases.
About this task
As part of the process for decreasing lock entry size,
you must restart the members, which results in a group restart. Because
you quiesce work before changing the lock entry size, the group restart
should be relatively quick. Nonetheless, decreasing the lock entry
size is a disruptive procedure. Consider doing this only in situations
when the lock entry size is set too high for the number of members
in the group, and you cannot alleviate the false contention within
the storage boundaries you have.
Procedure
To decrease the lock entry size:
- Quiesce all members of the group, using the following command:
-DB1A STOP DB2 MODE(QUIESCE)
- If IRLM is not automatically stopped along with Db2, enter the z/OS® command:
- Force all connections to the lock structure to disconnect
by issuing the following z/OS command:
SETXCF FORCE,CONNECTION,STRNAME=strname,CONNAME=ALL
- Force the deallocation of the lock structure by issuing
the following z/OS command:
SETXCF FORCE,STRUCTURE,STRNAME=strname
- Change the lock entry size for at least one IRLM. (You
should change the value for all of them.)
If you change
the IRLM startup procedure directly, the parameter that you change
is called MAXUSRS. The value of LOCK ENTRY SIZE is translated during
the Db2 installation or migration
process. The value that you enter on the IRLM parameter directly is
not the same as the value you put in the LOCK ENTRY SIZE field of
installation panel DSNTIPJ.
- Start the member and IRLM that have the updated value.
(You must start the updated member first.)
- Start all other members.