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.
||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)
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
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
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:
- Stop Cassandra. For details, see Manage Apache Cassandra.
CASSANDRA_HOME/conf if necessary.
Enable Apache Cassandra debug logging
You can enable Cassandra debug logging using any of the following approaches:
- You can specify a
logger in the
cassandra/conf/logback.xml configuration file as follows:
<logger name "org.apache.cassandra.transport" level=DEBUG/>
- You can use the
nodetool setlogginglevel command as follows:
nodetool setlogginglevel org.apache.cassandra.transport DEBUG
- The JConsole tool enables you to configure Cassandra logging using JMX. For example, you can invoke
setLoggingLevel and specify
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.