Database Reference
In-Depth Information
Replacing a node
More often than not, you find yourself in a less than situation where you do not really want
to remove a dead node; instead, you want to replace it. The reasons can be many, your
cloud service provider finds that a node is sitting on degraded hardware and kills the nodes
with a notification mail to you.
All versions after Cassandra Version 1.2 have simplified replacing a node to merely run-
ning one command. Here are the steps to replace a node:
1. Install Cassandra on the new node. Make sure
conf/cassandra.yaml
has all
the custom changes that exist in other nodes. (The best way to do this is to copy
cassandra.yaml
from a live node, and change the node-specific setting.)
2. Make sure you have got the following variables right:
cluster_name
,
end-
point_snitch
,
listen_address
,
broadcast_address
, and
seeds
.
3. Make sure the data directories are clean. If you are reusing a node that used to be a
part of Cassandra cluster, it can possibly lead to a startup failure if the data direct-
ory has old data.
4. Start Cassandra with the
cassandra.replace_address
environment vari-
able set as the address of the dead node that this node is replacing. This can be
done either by editing
cassandra-env.sh
or by adding a line like this:
JVM_OPTS="$JVM_OPTS
-Dcassandra.replace_address=DEAD_NODE_ADDRESS"
You can also start Cassandra with this variable:
$ bin/cassandra
-Dcassandra.replace_address=DEAD_NODE_ADDRESS
This is how it looks before the removal of the dead node:
