November 2010
Intermediate to advanced
328 pages
9h 38m
English
Content preview from Cassandra: The Definitive GuideBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Chapter 10. Maintenance
In this chapter, we look at some things you can do to keep Cassandra healthy. So put your operations hat on, and let’s get started.
The Nodetool ships with Cassandra and can be found in <cassandra-home>/bin. This is a command-line program that offers a rich array of ways to look at your cluster, understand its activity, and modify it. Nodetool lets you get limited statistics about the cluster, see the ranges each node maintains, move data from one node to another, decommission a node, and even repair a node that’s having trouble.
Note
Many of the tasks in Nodetool overlap with functions available in
the JMX interface. This is because, behind the scenes, Nodetool is
invoking JMX using a helper class called NodeProbe.
So JMX is doing the real work, the NodeProbe class
is used to connect to the JMX agent and sort out the data, and the
NodeCmd class is used to present it in an
interactive command-line
interface.
To use Nodetool, you need to have the same environment as Cassandra itself; that is, it requires the same classpath and logging files.
Note
The command-line Nodetool is a wrapper
around org.apache.cassandra.tools.NodeCmd. Take a look at
the source for that class if you need to know more about exactly
what it’s doing.
Starting Nodetool is a breeze. Just open a terminal, navigate to <cassandra-home>, and enter the following command:
$bin/nodetool
Running it this way will error out, but you also cause the program to print a list of available commands, which are covered ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.