关于cassandra 读取百万级数据：报错

当从cassandra中读取5百万条数据时，出现连接超时异常

010-11-29 14:31:08,390 INFO [me.prettyprint.cassandra.service.JmxMonitor] - Registering JMX me.prettyprint.cassandra.service:ServiceType=gg,MonitorType=hector
2010-11-29 14:31:08,453 INFO [me.prettyprint.cassandra.service.CassandraClientPoolImpl] - Creating a CassandraClientPool
2010-11-29 14:31:08,453 INFO [me.prettyprint.cassandra.service.CassandraClientPoolImpl] - Creating a CassandraClientPool with the following configuration: 192.168.0.136(192.168.0.136):9160
2010-11-29 14:31:18,671 WARN [me.prettyprint.cassandra.service.FailoverOperator] - Got a TimedOutException from 192.168.0.136. Num of retries: 1 (thread=main)
2010-11-29 14:31:18,671 INFO [me.prettyprint.cassandra.service.FailoverOperator] - Skipping to next host (thread=main). Current host is: 192.168.0.136
2010-11-29 14:31:18,671 INFO [me.prettyprint.cassandra.service.FailoverOperator] - Invalidating client CassandraClient<192.168.0.136:9160-1> (thread=main)
2010-11-29 14:31:18,687 INFO [me.prettyprint.cassandra.service.FailoverOperator] - Skipped host (thread=main). New client is CassandraClient<192.168.0.136:9160-2>
2010-11-29 14:31:28,796 WARN [me.prettyprint.cassandra.service.FailoverOperator] - Got a TimedOutException from 192.168.0.136. Num of retries: 0 (thread=main)
2010-11-29 14:31:28,796 INFO [me.prettyprint.cassandra.service.FailoverOperator] - Invalidating client CassandraClient<192.168.0.136:9160-2> (thread=main)
2010-11-29 14:31:28,796 ERROR [com.ggms.main.HectorClient] - HectorClient.class-->getCount
TimedOutException()
    at org.apache.cassandra.thrift.Cassandra$get_count_result.read(Cassandra.java:8387)

求助！！！！！！！！！！！！！！！１