Database Reference
In-Depth Information
To fetch more information on the Cassandra cluster, like current state, load, and as-
signed token, we can run the
status
command:
vivek@vivek-Vostro-3560:~/software/local-cluster/node1$
bin/nodetool status
Running this command prints the data shown in following output:
Datacenter: datacenter1
=======================
Status=Up(U)/Down(D)
|/ State=Normal(N)/Leaving(L)/Joining(J)/Moving(M)
Status/ Address Load Tokens Owns Host
ID Rack
State (effective)
UN 127.0.0.1 59.82 KB 129 166.7%
718d384e-c8c2-4355-bf9b-1bfa60be2d99 Rack1
UN 127.0.0.2 66.54 KB 256 166.7%
cb9da211-6948-4c21-b5f5-5ee660cd9355 Rack1
UN 127.0.0.3 50.31 KB 256 66.7%
74ee5df6-d990-4deb-9144-501c349308d6 Rack1
The preceding output is similar to the first output example in this section. The only
differences are the
Tokens
and
Host ID
fields. Here the
Tokens
column shows the
number of tokens set for each node, and the
Host ID
is the network ID of the data
node. It's a UUID value assigned by Cassandra for each node.
That's how we can monitor the cluster ring status and its information. In the next
section we will discuss how to decommission a live data node.
Decommissioning a Node
We can also decommission a node using the nodetool utility. In this exercise, we will
decommission a node by using the
decommission
command and then verify that it
is decommissioned by checking the cluster ring status.
