How to check if a scheduled nodetool repair ran successfully

Summary

This article shows how to check the outcome of a scheduled (e.g. cron) nodetool repair from the logs.

Repair session

A repair session, otherwise known as "anti-entropy", is identified by a session UUID in the Cassandra system.log. To determine the start of a repair session, search for a RepairSession.java entry with the phrase new session:, for example:

 INFO [AntiEntropySessions:1] 2015-03-01 10:02:53,261 RepairSession.java (line 244) [repair #2e7009b0-c03d-11e4-9012-99a64119c9d8] new session: will sync myCluster/10.1.2.3, /10.1.2.4, /10.1.2.5 on range (0,4611686018427387904] for myKS.myCF

In this example, the session UUID is 2e7009b0-c03d-11e4-9012-99a64119c9d8. To view all entries in the log relating to this session, filter the log for this particular session ID.

Note that depending on how repairs are managed, there could be multiple sessions in the logs.

Completion

To check if the session completed successfully, filter the log with the appropriate session UUID and the last entry will have the phrase session completed successfully.

From the example above, the corresponding completed repair session log entry is as follows:

 INFO [AntiEntropySessions:1] 2015-03-01 10:02:56,245 RepairSession.java (line 282) [repair #2e7009b0-c03d-11e4-9012-99a64119c9d8] session completed successfully

Additional information

For more information on investigating an unsuccessful repair session, see Troubleshooting hanging repairs.