Coupling facility failure scenarios

Coupling facility failure scenarios include connectivity failures and structure failures.

Connectivity failure to the SCA or lock structure

The following table summarizes what happens when there are connectivity failures to the SCA.

Table 1. Summary of connectivity failures to the SCA
Active SFM policy? Weighted loss < REBUILDPERCENT? Db2 response Operational response
No Not applicable Each affected member issues: 
DSN7501A
00F70600
Db2 comes down. Connection is deleted; structure remains allocated.		 Options include:
  • Fix problem
  • Restart failed member on system that is connected to coupling facility
  • Manually rebuild onto another coupling facility.
Yes Yes Each affected member issues: 
DSN7501A
00F70600
Db2 comes down. Connection is deleted; structure remains allocated.		 Options include:
  • Fix problem
  • Restart failed member on system that is connected to coupling facility
  • Manually rebuild onto another coupling facility.
Yes No Automatic rebuild. 
DSN7503I
 None needed.

The following table summarizes what happens when there are connectivity failures to the lock structure.

Table 2. Summary of connectivity failures to the lock structure
Active SFM policy? Weighted loss < REBUILDPERCENT? Db2 response Operational response
No Not applicable Each affected member issues: 
DXR136I
00E30105
Db2 comes down. Connection is failed-persistent; structure remains allocated.		 Options include:
  • Fix problem
  • Restart failed member on system that is connected to coupling facility
  • Manually rebuild onto another coupling facility.
Yes Yes Each affected member issues: 
DXR136I
00E30105
Db2 comes down. Connection is failed-persistent; structure remains allocated.		 Options include:
  • Fix problem
  • Restart failed member on system that is connected to coupling facility
  • Manually rebuild onto another coupling facility.
Yes No 
DXR143I
Automatic rebuild. 
DXR146I
 None needed.

Connectivity failure to non-duplexed group buffer pools

The following table summarizes what happens when there are connectivity failures to the group buffer pools.

Table 3. Summary of connectivity failures for non-duplexed group buffer pools
Connectivity lost from Weighted loss < REBUILDPERCENT? Db2 response Operational response
100% of members connected to a group buffer pool that is defined with GBPCACHE(YES) No Each affected member issues: 
DSNB303E
DSNB228I
Add pages to logical page list, if necessary. 
DSNB250E
DSNB314I* rsn=100%
DSNB304I*
Damage assessment, GRECP page sets. 
DSNB320I
DSNB321I
DSNB353I
DSNI006
DSNI021
DSNI051
DSNB354I
DSNB305I*
 None needed if the group buffer pool is defined with AUTOREC(YES), and Db2 successfully recovers the page sets. Otherwise, enter START DATABASE commands.
100% of members connected to a group buffer pool that is defined with GBPCACHE(NO) No Automatic rebuild. 
DSNB331I
DSNB338I
 None needed.
A subset of members connected to some or all group buffer pools. Yes Each affected member issues: 
DSNB303E
DSNB228I
DSNB313I rsn=LOSSCONN
Quiesce applications that use the group buffer pool. Add pages to logical page list if necessary. 
DSNB250E
DSNB311I, DSNB312I
Disconnect GBPx failed-persistent. 
DSNB309I
 Options include:
  • Fix the problem.
  • Manually rebuild the structure onto another coupling facility.
  • Stop and restart Db2 on a system that is connected to the coupling facility.

Enter START DATABASE commands to recover logical page list entries.
A subset of members connected to some or all group buffer pools. No Automatic rebuild. 
DSNB331I
DSNB332I
DSNB333I 1
DSNB338I
 None needed.
Note:
  1. Issued by the structure owner.

Structure failures

The following table summarizes what happens to each structure if there is a structure failure. This information is for non-duplexed group buffer pools.

Table 4. Summary of structure failures, by structure type
Failed structure Db2 response Operational response
SCA 
DSN7502I
Automatic rebuild 
DSN7503I
 None needed.
Lock structure 
DXR143I
Automatic rebuild 
DXR146I
 None needed.
Group buffer pool that is defined with GBPCACHE(YES) 
DSNB228I
DSNB314I rsn=STRFAIL
Add pages to logical page list, if necessary. 
DSNB250E
Damage assessment, GRECP page sets. 
DSNB304I
DSNB320I  DSNB321I
DSNI006
DSNI021
DSNB305I
 None needed if the group buffer pool is defined with AUTOREC(YES) and Db2 successfully recovers the page set. Otherwise, enter START DATABASE commands.
Group buffer pool that is defined with GBPCACHE NO Automatic rebuild. 
DSNB331I
DSNB338I
 None needed.

Connectivity failures for the duplexed group buffer pools

For duplexed group buffer pools, a failure response is the same for both a loss of structure and for lost connectivity, as shown in the following table.
Table 5. Summary of scenarios for both a loss of structure and lost connectivity for duplexed group buffer pools
Structure loss Db2 response Operational response
Primary Switch to secondary in simplex mode 
DSNB744I
DSNB745I
If DUPLEX(ENABLED) then reduplexing is attempted. 		If the system did not automatically reduplex, correct the problem with the failed coupling facility. If you want to restart duplexing, use the z/OS® SETXCF command.
Secondary Revert to primary in simplex mode 
DSNB743I
DSNB745I
If DUPLEX(ENABLED) then reduplexing is attempted.		 If the system did not automatically reduplex, correct the problem. If you want to restart duplexing, use the SETXCF command.
Both (loss of structure or 100 % LOSSCONN) Damage assessment, GRECP page sets. None needed if the group buffer pool is defined with AUTOREC(YES) and Db2 successfully recovers the page set. Otherwise, enter START DATABASE commands.