Does WSO2 support MySQL Master/Slave Cluster? - wso2

Question

I have tried to use MySQL Master/Slave cluster in WSO2 cluster deployment, but failed when startup. Does WSO2 only support MySql Share-Nothing cluster? How does it support MySQL Master/Slave?
My datasource was configured as below:
<datasource>
<name>WSO2REG_LOCAL</name>
<description>The datasource used for registry</description>
<jndiConfig>
<name>jdbc/WSO2REG_LOCAL</name>
</jndiConfig>
<definition type="RDBMS">
<configuration>
<url>jdbc:mysql:replication://wso2dbmaster:3306,wso2dbslave1:3306,wso2dbslave2:3306/WSO2_REG_LOCAL_AM_GW_MGR_1?roundRobinLoadBalance=true;autoReconnect=true;</url>
<username>test</username>
<password>test</password>
<driverClassName>com.mysql.jdbc.ReplicationDriver</driverClassName>
<defaultAutoCommit>false</defaultAutoCommit>
<maxActive>50</maxActive>
<maxWait>60000</maxWait>
<testOnBorrow>true</testOnBorrow>
<validationQuery>SELECT 1</validationQuery>
<validationInterval>30000</validationInterval>
</configuration>
</definition>
</datasource>
<datasource>
<name>WSO2REG_DB</name>
<description>This shared datasource used for registry</description>
<jndiConfig>
<name>jdbc/WSO2REG_DB</name>
</jndiConfig>
<definition type="RDBMS">
<configuration>
<url>jdbc:mysql:replication://wso2dbmaster:3306,wso2dbslave1:3306,wso2dbslave2:3306/WSO2_REG_DB?roundRobinLoadBalance=true;autoReconnect=true;</url>
<username>test</username>
<password>test</password>
<driverClassName>com.mysql.jdbc.ReplicationDriver</driverClassName>
<defaultAutoCommit>false</defaultAutoCommit>
<maxActive>50</maxActive>
<maxWait>60000</maxWait>
<testOnBorrow>true</testOnBorrow>
<validationQuery>SELECT 1</validationQuery>
<validationInterval>30000</validationInterval>
</configuration>
</definition>
</datasource>
registry.xml was configured as below:
<currentDBConfig>wso2registry</currentDBConfig>
<readOnly>false</readOnly>
<enableCache>true</enableCache>
<registryRoot>/</registryRoot>
<dbConfig name="wso2registry">
<dataSource>jdbc/WSO2REG_LOCAL</dataSource>
</dbConfig>
<dbConfig name="sharedregistry">
<dataSource>jdbc/WSO2REG_DB</dataSource>
</dbConfig>
<remoteInstance url="https://localhost:9443/registry">
<id>instanceid</id>
<dbConfig>sharedregistry</dbConfig>
<readOnly>false</readOnly>
<enableCache>true</enableCache>
<registryRoot>/</registryRoot>
<cacheId>wso2db#jdbc:mysql:replication://wso2dbmaster:3306,wso2dbslave1:3306,wso2dbslave2:3306/WSO2_REG_DB?roundRobinLoadBalance=true;autoReconnect=true;</cacheId>
</remoteInstance>
Exception occurred as below when starting up.
TID: [0] [AM] [2015-03-09 13:30:51,728] ERROR {org.wso2.carbon.registry.core.internal.RegistryCoreServiceComponent} - Unable to create fixed remote mounts. {org.wso2.carbon.registry.core.internal.RegistryCoreServiceComponent}
org.wso2.carbon.registry.core.exceptions.RegistryException: An exception occurred while executing handler chain. null
....
ID: [0] [AM] [2015-03-09 13:31:03,417] ERROR {org.wso2.carbon.registry.core.dataaccess.TransactionManager} - Failed to rollback transaction. {org.wso2.carbon.registry.core.dataaccess.TransactionManager}
java.sql.SQLException: Total number of available connections are less than the total number of rollbacked or committed connections
at org.wso2.carbon.registry.core.jdbc.dataaccess.JDBCDatabaseTransaction$ManagedRegistryConnection.rollback(JDBCDatabaseTransaction.java:1284)
at org.wso2.carbon.registry.core.jdbc.dataaccess.JDBCTransactionManager.rollbackTransaction(JDBCTransactionManager.java:120)
at org.wso2.carbon.registry.core.jdbc.EmbeddedRegistry.rollbackTransaction(EmbeddedRegistry.java:447)
at org.wso2.carbon.registry.core.jdbc.EmbeddedRegistry.get(EmbeddedRegistry.java:552)
at org.wso2.carbon.registry.core.caching.CacheBackedRegistry.get(CacheBackedRegistry.java:180)
at org.wso2.carbon.registry.core.session.UserRegistry.get(UserRegistry.java:524)
...

Answer 1

Normally the reason for this error is, you are using the same database for local registry space and governance space.
if you are using the same jdbc/WSO2REG_DB database as local and governance registry spaces. It is wrong by definition. It is not correct to share local registry space between any nodes in a cluster. Ideally, you could use the default H2 database as local registry database (jdbc/WSO2CarbonDB). Basically you need to keep following configuration in registry.xml file by pointing to H2 db. Just found some blog about same error which may be helpful.
<currentDBConfig>wso2registry</currentDBConfig>
<dbConfig name="wso2registry">
<dataSource>jdbc/WSO2CarbonDB</dataSource>
</dbConfig>