Diagnose the causes of problems with data store exclusive access
locks and examine possible causes to the problems.
About this task
Each messaging engine establishes an exclusive lock
on its data store. While the messaging engine is running, it maintains that
lock to ensure the integrity of the data within the data store.
Compare
your symptoms with those listed in the following table and examine the possible
solutions:
Symptom |
Cause |
Solution |
The messaging engine cannot start nor
failover to another server. The messaging engine writes error message CWSIS1519 |
The messaging engine cannot connect to the database that you specified
in the data source that you configured to enable the messaging engine to access
its data store. |
|
After a delay of many minutes, the messaging engine cannot failover
to another server and writes error message CWSIS1519. |
Another instance of the same messaging engine is holding the data
store lock, or the database has not released a data store lock that was held
by a failed instance of the same messaging engine. |
- If you can connect to the database, another instance of the messaging
engine might hold a lock on the data store. Check for other running instances
of the same messaging engine. Only one instance of each messaging engine can
run in a cluster at a given time.
- After the failure of an instance of a messaging engine or an application
server that is running in a cluster, the database might not have released
the database locks that comprise the data store lock. Use the administration
tools for your relational database management system to examine the locks
on the SIBOWNER table. If the
database is still holding locks after the failure of a server, ensure that
you configure the liveness checking of the network connection between the
application server and the database server to enable prompt failover. For
example, examine the TCP keep alive parameter.
If you are
using DB2 for z/OS,
you can examine the DB2 Idle Thread Timeout.
You might have to use
your database administration tools to force the release of the lock on the
data store.
|
The messaging engine fails to start and writes error messages CWSIS1535 and CWSIS1519 |
The identifiers in the SIBOWNER table
do not match those of the messaging engine. |
- Check that the data source that you configured for the messaging engine
refers to the correct database.
- If the MEUUID identifiers do not match, check that
a previous messaging engine did not use the same tables. If the tables already
exist, DROP the tables and CREATE them again for the new
messaging engine.
- If the INCUUID identifiers do not match, another
instance of the same messaging engine is running and has acquired the lock.
Check for other running instances of the messaging engine.
|
The messaging engine starts but then stops and writes error message CWSIS1519. |
The messaging engine has lost its lock on the data store. |
- Check that you have connectivity to the database through the data source
that you specified. The messaging engine might have lost network connectivity
and be unable to maintain a connection with the database.
- If you can connect to the database, another instance of the messaging
engine might have started and obtained a lock on the data store. Check for
other running instances of the messaging engine.
|