Hello Everybody,


I am trying to merge two clusters into a single cluster ( the rationale being easier administration apart from better load balancing etc) 


The plan is to rename a cluster (QAPERF1) as the same name as the second cluster (QAPERF2). Then alter the cassandra-toppology.properties and make them appear as different Dcs. Then finally alter replication settings and rebuild nodes of course after changing the seeds. It is made sure that the schema is same across the  two clusters. This is a test on apache cassandra 1.2.4. 


In the process of  renaming an existing cluster, I have followed the instructions here : http://wiki.apache.org/cassandra/FAQ#clustername_mismatch


I get the following when restarting the node after restarting the first node after cluster name change ( The other nodes are yet to be restarted). It looks like the old cluster name has not taken into effect in spite of completing the flush as mentioned in the wiki. 


ERROR [main] 2013-06-24 04:44:35,812 CassandraDaemon.java (line 222) Fatal exception during initialization

org.apache.cassandra.exceptions.ConfigurationException: Saved cluster name QAPERF1 != configured name QAPERF2

at org.apache.cassandra.db.SystemTable.checkHealth(SystemTable.java:447)

at org.apache.cassandra.service.CassandraDaemon.setup(CassandraDaemon.java:218)

at org.apache.cassandra.service.CassandraDaemon.activate(CassandraDaemon.java:411)

at org.apache.cassandra.service.CassandraDaemon.main(CassandraDaemon.java:454)


In the process of reverting it back, I changed the configuration file back to have the old cluster name and now I get this exception. 


ERROR [main] 2013-06-24 04:48:34,746 CassandraDaemon.java (line 428) Exception encountered during startup

java.util.NoSuchElementException

at java.util.ArrayList$Itr.next(ArrayList.java:794)

at org.apache.cassandra.db.SystemTable.upgradeSystemData(SystemTable.java:164)

at org.apache.cassandra.db.SystemTable.finishStartup(SystemTable.java:98)

at org.apache.cassandra.service.CassandraDaemon.setup(CassandraDaemon.java:317)

at org.apache.cassandra.service.CassandraDaemon.activate(CassandraDaemon.java:411)

at org.apache.cassandra.service.CassandraDaemon.main(CassandraDaemon.java:454)


Can experts please advise what is the best way to rename a cluster in case I want to change it for version 1.2.4 ? Thanks for your time. 


Regards,

Ananth