Cassandra Nodes Test

Cassandra is a distributed database system using a shared nothing architecture. A single logical database is spread across a cluster of nodes and thus the need to spread data evenly amongst all participating nodes. Data is evenly divided around its cluster of nodes. Each node is responsible for a portion of data.

If a node becomes unreachable, then, that portion of data may become unavailable, provided the data is not replicated to other nodes. Therefore, it becomes mandatory to monitor the nodes that are unavailable and unreachable. The Cassandra Nodes test helps administrators to keep track on the nodes constantly.

This test helps administrators to figure out the count of the nodes that are unavailable and unreachable. In addition, this test also reports the number of nodes that joined the cluster, left the cluster and migrated to another cluster. Using this information, administrators can figure out the nodes that are frequently unreachable and initiate further investigation to avoid the nodes from being unreachable too often.

Target of the test : A Cassandra Database

Agent deploying the test : An external/remote agent.

Outputs of the test : One set of results for the target Cassandra Database node being monitored.

Configurable parameters for the test
Parameters Description

Test Period

How often should the test be executed.

Host

The host for which the test is to be configured.

Port

The port on which the specified host listens. By default, this is 9042.

JMX Remote Port

Here, specify the port at which the JMX listens for requests from remote hosts. Ensure that you specify the same port that you configured in the cassandra-env.sh file (if the target Cassandra Database node is installed on a Unix host) or the cassandra-env.ps1 file (if the target Cassandra Database node is installed on a Windows host) in the <CASSANDRA_HOME> directory used by the target Cassandra Database node. To know how to specify the remote port, refer to Enabling JMX Support for JRE.

JMX User and JMX Password

If JMX requires authentication only (but no security), then ensure that the user and password parameters are configured with the credentials of a user with read-write access to JMX. To know how to create this user, refer to Configuring the eG Agent to Support JMX Authentication.

Confirm Password

Confirm the Password by retyping it in this text box.

Detailed Diagnosis

To make diagnosis more efficient and accurate, the eG Enterprise suite embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option.

The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled:

  • The eG manager license should allow the detailed diagnosis capability
  • Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Available nodes

Indicates the number of nodes available in the cluster.

Number

The detailed diagnosis of this measure lists the IP address of the nodes that are available in the cluster.

Joining nodes

Indicates the number of nodes that joined the cluster.

Number

The detailed diagnosis of this measure lists the IP address of the nodes that joined the cluster.

Leaving nodes

Indicates the number of nodes that left the cluster.

Number

The detailed diagnosis of this measure lists the IP address of the nodes that left the cluster.

Moving nodes

Indicates the number of nodes that were migrating to another cluster from the cluster.

Number

The detailed diagnosis of this measure lists the IP address of the nodes that migrated to another cluster.

Unreachable nodes

Indicates the number of nodes that were unreachable in the cluster.

Number

The detailed diagnosis of this measure lists the IP address of the nodes that are unreachable.

By identifying the nodes that are unreachable, administrators can initiate further investigation on why the nodes are unreachable and troubleshoots the issues related to those nodes.