Perform essential Apache Cassandra operations

This topic describes the minimum essential operations that are required to maintain a healthy Apache Cassandra high availability (HA) cluster.

Repair inconsistent nodes

Apache Cassandra has different ways to maintain data consistency across the cluster during normal runtime processing. However, to resolve any data inconsistencies that could not be resolved by normal runtime processes, you must run an external repair process on a regular basis.

For standard HA configurations, it is best to run repair once per week (during a quiet period) on each node in the cluster.

Caution   The repair must only be executed on one node at a time. You must therefore adjust the repair schedule for each node in the cluster to avoid overlap.

Schedule repair using crontab

When scheduling Cassandra repair events, it is best to use the crontab command of the user running the Cassandra process.

To edit the cron table of this user, execute sudo crontab -u CASSANDRA_USER -e and paste the matching node block from the following examples:

Example cron table entries for three-node cluster repairing one node per day (Saturday to Monday)

Node 1:

Run full repair at 1 a.m. every Saturday:

0 1 * * 6 PATH_TO_CASSANDRA/bin/nodetool CONNECTION_SECURITY_PARAMS repair -pr --full > PATH_TO_CASSANDRA/logs/last_repair.log 2>&1

Node 2:

Run full repair at 1 a.m. every Sunday:

0 1 * * 0 PATH_TO_CASSANDRA/bin/nodetool CONNECTION_SECURITY_PARAMS repair -pr --full > PATH_TO_CASSANDRA/logs/last_repair.log 2>&1

Node 3:

Run full repair at 1 a.m. every Monday:

0 1 * * 1 PATH_TO_CASSANDRA/bin/nodetool CONNECTION_SECURITY_PARAMS repair -pr --full > PATH_TO_CASSANDRA/logs/last_repair.log 2>&1

See also Clean up Cassandra repair history.

Replace dead nodes

If a node is down for more than 10 days, it should be replaced. For details on replacing dead Cassandra nodes, see the Replacing a dead node or dead seed node documentation.

Reconfigure an existing Apache Cassandra installation from scratch

There is no need to reinstall Cassandra from scratch. Instead, you can move the Cassandra data files and restore the cassandra.yaml configuration file if necessary (if you updated Cassandra configuration). Perform the following steps:

  1. Stop Cassandra. For details, see Manage Apache Cassandra.
  2. Move CASSANDRA_HOME/data to CASSANDRA_HOME/data/OLD-DATA-DATE.
  3. Restore cassandra.yaml in CASSANDRA_HOME/conf if necessary.

Enable Apache Cassandra debug logging

You can enable Cassandra debug logging using any of the following approaches:

  • logback.xml
  • You can specify a logger in the cassandra/conf/logback.xml configuration file as follows:

<logger name "org.apache.cassandra.transport" level=DEBUG/>

  • nodetool
  • You can use the nodetool setlogginglevel command as follows:

nodetool setlogginglevel org.apache.cassandra.transport DEBUG

  • JConsole
  • The JConsole tool enables you to configure Cassandra logging using JMX. For example, you can invoke setLoggingLevel and specify org.apache.cassandra.db.StorageServiceMBean and DEBUG as parameters. For more details, see the next section.

For more details on enabling logging, see the following, which also applies to Cassandra 2.2:

Monitor a Cassandra cluster using JMX

You can use Java Management Extensions to monitor and manage performance in a Cassandra cluster. For details, see the Monitoring a Cassandra cluster documentation.

Upgrade your Cassandra version

For details on upgrading your Cassandra version, see Upgrade Apache Cassandra in the API Gateway Upgrade Guide.

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