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Wednesday, 2 September 2015
WebSphere Application Server 8.5.5 and DB2 10.5 - High Availability for Disaster Recovery - Like Manuel, I learn ....
I've been testing, experimenting and documenting my experiences with IBM DB2 10.5, specifically with the High Availability for Disaster Recovery (HADR) configuration, in the context of making a WebSphere Application Server (WAS) configuration more resilient.
To that end, I've been scripting the necessary configuration to allow WAS to use the DB2 Automatic Client Reroute Options: -
in order that WAS can connect to another DB2 server within the "cluster" in the situation where the primary server, to which the JDBC Data Source normally points: -
Now, in the first screenshot above, you'll notice that the Client reroute server list JNDI name is left blank.
This is by design :-)
Initially, I was populating that particular property, being unaware as to what it did :-)
That was a BAD move.
Basically, the property is ONLY used if one creates a second JDBC Data Source to point at the second, standby database server.
However, the use of the other parameters, Alternate Server Names and Alternate Port Numbers makes this unnecessary.
Note 1: If you choose to use Client reroute server list JNDI name, you do not need to supply Alternate server names and Alternate port numbers (and vice versa). Note 2: The Client reroute server list JNDI name should be a unique JNDI name, different from the JNDI Name used in the previous step.
So, back to me, and this is what I was seeing when I attempted to test a JDBC Data Source whilst the primary ( configured ) DB2 server was down down down: -
The test connection operation failed for data source Monitor_Database on server dmgr at node Dmgr with the following exception: java.sql.SQLNonTransientException: [jcc][t4][4.11.69] Exception java.net.ConnectException: Error opening socket to server bpm856.uk.ibm.com/192.168.33.200 on port 60,006 with message: Connection refused. ERRORCODE=-4499, SQLSTATE=08001 DSRA0010E: SQL State = 08001, Error Code = -4,499. View JVM logs for further details.
with this in SystemErr.log: -
[02/09/15 15:18:41:143 BST] 00000107 SystemErr R java.sql.SQLNonTransientException: [jcc][t4][4.11.69] Exception java.net.ConnectException: Error opening socket to server bpm856.uk.ibm.com/192.168.33.200 on port 60,006 with message: Connection refused. ERRORCODE=-4499, SQLSTATE=08001 DSRA0010E: SQL State = 08001, Error Code = -4,499 ...