Oracle

December 20, 2009

FCF

Filed under: Uncategorized — srivenu @ 9:37 am

I configured and tested FCF (Fast Connection Failover) setup for use by TIBCO application. I was using Metalink note – 433827.1. (I also found one example code snippet on http://www.idevelopment.info)

Since i did not want to install ONS on the middle tier, i was using “remote subscription” (this limits the debugging options on the client side). For testing i registered a new service in CRS. I used this in the JDBC connection URL. I tested with both vip and physical ip in the JDBC URL and both worked. I had the ONS ports opened on the server firewall.

One issue (or i thought it was an issue) i faced was related to the min number of connections in the cache after an instance shutdown. While testing, i used a value of 10 for both “MinLimit” & “InitialLimit”. On startup, the pool had a total of 10 connections, 5 each from instances 1 & 2. On shutdown abort of instance 1, i expected the JDBC application to open 5 new connections on instance 2 in lieu of the 5 closed connections on instance 1. But the connection count remained at 5. I scratched my head till i had a small “aha” moment on reading this in the oracle manual (http://download.oracle.com/docs/cd/B28359_01/java.111/b31224/concache.htm)

MinLimit
………….

Connections can fall below the minimum limit set on the connection pool when JDBC Fast Connection Failover DOWN events are processed. The processing removes affected connections from the pool. MinLimit will be honored as requests to the connection pool increase and the number of connections get past the MinLimit value.

One more test case i performed was to use a service name which wasn’t registered in the CRS, the code just failed with exception 17410 when it tried to use a connection from instance 1 (which was shutdown sometime after application startup). This was expected as no FAN events would be received by the JDBC application from ONS for this unregistered service name.

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