DB2 – Remote Connection Failure-00D31034 Abend

Problem: DB2 Connection failure causing jobs to fail.Failure REASON=00D31034 .


Reason:
MAX REMOTE CONNECTED limit was reached and the conversation was abnormally de-allocated. The new remote thread was not allowed to connect to DB2 . Found connection from one of the interface server was not disconnecting the old threads. That caused increase in number of Inactive threads.
Omega-Mon DDF Statistics
> DISTRIBUTED DATA FACILITY STATISTICS
DFST
+ Collection Interval: REALTIME Start: 01/20 11:20:11
+ Report Interval: 1 sec End: 01/20 11:20:12
+
+ Location Name = DBXX DDF Status = ACTIVE
+ DDF CPU Rate = 00.3% Dist Allied Threads = 0
+ Active DBATs = 5 Inactive DBATs = 76

+ DDF Send Rate = 318K/sec DDF Receive Rate = 21K/sec
+ Resync Attempts = 0 Resync Successes = 0
+ Cold Start Connections = 0 Warm Start Connections = 0
+ DBAT Queued = 0 Conversations Dealloc = 0
+ HWM Remote Connections = 90 HWM Active DBATs = 63

+ Max DB Access (MAXDBAT)= 90 HWM Inactive DBATs = 91

+

+ Remote Location Name = DRDA REMOTE LOCS
+
The system had both MAXDBAT and CONDBAT set to 90.
Solution: The Interface server was planned to be restarted to disconnect old connections. And interface connection to analysed to get the reason for threads not getting disconnected.
As temporary solution the CONDBAT was increased from 90 to 120 which do not need a DB2 Subsystem bounce as it a dynamic change to ZParm value.


Lesson’s Learnt :
CON DB Access (CONDBAT) – Maximum Remote connection limit set for the DB2 Subsystem
HWM Remote Connections - Maximum connection reached since the last IPL.
HWM Active DBATs - Maximum Active connection reached since the last IPL
HWM Inactive DBATs - Maximun Inactive connection reached since the last IPL
Active DBATs - Currrent Active DB2 Threads
Inactive DBATs - Current Inactive DB2 Threads

If Active DBATs + Inactive DBATs connections reaches the CONDBAT any new remote DB2 connections will fail.

Active DBATs + Inactive DBATs should be always less than CONDBAT Value.

 

DB2V10-Enhancement to prevent remote DB2 Connection failure :  To help prevent 00D31034 failure from occurring, two system parameters were introduced by APAR PM43293: MAXCONQN and MAXCONQW. MAXCONQN controls the number of connections that can be waiting on a DBAT to come available and MAXCONQW specifies the amount of time a connection can wait for a DBAT.

Note: MAXCONQN and MAXCONQW can be set to ON, OFF, or to a specific value; the default for both MAXCONQN and MAXCONQW is OFF.