Database Reference
In-Depth Information
DEBUG 15:45:20,789 Started hinted handoff for endPoint /192.168.1.7
DEBUG 15:45:20,800 Finished hinted handoff for endpoint /192.168.1.7
DEBUG 15:46:17,638 Disseminating load info ...
This output shows that I have two nodes in my cluster: the node I just started, which is listening
on 192.168.1.5, and the node that was already up and running, which is listening on 192.168.1.7.
Dynamic Ring Participation
Nodes in a Cassandra cluster can be brought down and brought back up without disruption to the
rest of the cluster (assuming a reasonable replication factor and consistency level). Say that we
have started a two-node cluster as described earlier in
Creating a Cluster
. We can cause an error
to occur that will take down one of the nodes, and then make sure that the rest of the cluster is
still OK:
INFO 15:34:18,953 Starting up server gossip
INFO 15:34:19,281 Binding thrift service to /192.168.1.7:9160
INFO 15:34:19,343 Cassandra starting up...
INFO 15:45:19,396 Node /192.168.1.5 is now part of the cluster
INFO 15:45:20,176 InetAddress /192.168.1.5 is now UP
INFO 16:13:36,476 error writing to /192.168.1.5
INFO 16:13:40,517 InetAddress /192.168.1.5 is now dead.
INFO 16:21:02,466 error writing to /192.168.1.5
INFO 16:21:02,497 error writing to /192.168.1.5
The error message will repeat until the 1.5 node comes back up. Running Nodetool will indicate
that it's down now, while the other node is still up.
So we bring it back up and check the logs at 1.7. Sure enough, Cassandra has automatically de-
tected that the other participant has returned to the cluster and is again open for business:
INFO 16:33:48,193 error writing to /192.168.1.5
INFO 16:33:51,235
error writing to /192.168.1.5
INFO 16:34:20,126 Standard2 has reached its threshold; switching in a fresh Mem
table at CommitLogContext(file='/var/lib/cassandra/commitlog\CommitLog-127759165
782.log', position=752)
INFO 16:34:20,173 Enqueuing flush of Memtable(Standard2)@7481705
INFO 16:34:20,251 Writing Memtable(Standard2)@7481705
INFO 16:34:20,282 LocationInfo has reached its threshold; switching in a fresh
Memtable at CommitLogContext(file='/var/lib/cassandra/commitlog\CommitLog-127759
658782.log', position=752)
INFO 16:34:20,298 Enqueuing flush of Memtable(LocationInfo)@24804063
INFO 16:34:20,579 Completed flushing c:\var\lib\cassandra\data\Keyspace1\Standa
d2-1-Data.db
INFO 16:34:20,594 Writing Memtable(LocationInfo)@24804063
