Problem: a subset of members have lost connectivity (non-duplexed)

In a data sharing environment with simplexed structures, one or more members might lose connectivity to the coupling facility, while other members do not. This might happen if a link is detached between a system and the coupling facility.

This scenario assumes that the group buffer pool, lock, and SCA structures are simplexed, and have REBUILDPERCENT(1) specified in the CFRM policy, which is the recommended setting. With REBUILDPERCENT(1) specified, the group buffer pool, lock or SCA structures will automatically be rebuilt into an alternate coupling facility whenever a member loses connectivity to the structure.

Symptom

Some or all of the following messages appear, depending on which structures Db2 tries to access: 
DSNB303E -DB1A csect-name A LOSS OF CONNECTIVITY
WAS DETECTED TO GROUP BUFFER POOL gbpname
DSNB331 csect-name REBUILD STARTED FOR GROUP BUFFER POOL gbpname
REASON = LOSSCON
DSN7501A -DB1A csect-name SCA STRUCTURE sca-structure-name
CONNECTIVITY FAILURE
DXR143Iirlm-subsys-name REBUILDING LOCK STRUCTURE
BECAUSE IT HAS FAILED OR AN IRLM LOST CONNECTION TO IT

DSN7503Icsect-name SCA STRUCTURE sca-strname
REBUILD SUCCESSFUL

System action

The structures are automatically rebuilt into the alternate coupling facility.

When Db2 rebuilds the group buffer pool, it writes changed pages from the group buffer pool to the alternate structure specified in the CFRM policy. If Db2 determines that there is not enough space to hold the changed pages, it casts the pages out to disk instead and the following messages are issued:

  • DSNB331I
  • DSNB332I
  • DSNB333I
  • DSNB338I
For the SCA structure, the following message is issued: 
DSN7503Icsect-name SCA STRUCTURE sca-strname
REBUILD SUCCESSFUL
For the lock structure, the following message is issued: 
DXR143Iirlm-subsys-name REBUILDING LOCK STRUCTURE
BECAUSE IT HAS FAILED OR AN IRLM LOST CONNECTION TO IT