Prometheus TSDB corruption

What is Prometheus TSDB corruption

Understanding Prometheus and Its Purpose

Prometheus is an open-source systems monitoring and alerting toolkit originally built at SoundCloud. It is now a standalone open-source project and maintained independently of any company. Prometheus collects and stores its metrics as time series data, i.e., metrics information is stored with the timestamp at which it was recorded, alongside optional key-value pairs called labels.

Identifying Symptoms of TSDB Corruption

When Prometheus encounters TSDB (Time Series Database) corruption, you might observe errors such as 'corruption in the time series database' in the logs, or Prometheus might fail to start altogether. These symptoms are indicative of underlying issues with the database files.

Common Error Messages

Some common error messages that indicate TSDB corruption include:

unexpected end of JSON input checksum mismatch corruption in segment

Exploring the Root Cause of TSDB Corruption

TSDB corruption can occur due to several reasons, with the most common being abrupt shutdowns of the Prometheus server or disk issues. These events can lead to incomplete writes or corrupted data blocks, which in turn cause the database to become unreadable or unstable.

Impact of Disk Issues

Disk issues such as bad sectors or disk failures can also lead to data corruption. It is crucial to ensure that the storage medium used for Prometheus is reliable and monitored for health.

Steps to Fix TSDB Corruption

Fixing TSDB corruption involves either repairing the database or restoring it from a backup. Below are the steps you can follow:

Attempting to Repair the Database

Stop the Prometheus server to prevent further writes to the database. Run the following command to attempt a repair: prometheus tsdb repair --dir= Check the logs to see if the repair was successful.

Restoring from a Backup

If repair fails, restore the database from a recent backup. Ensure that the backup is placed in the correct data directory. Restart the Prometheus server and verify that it starts without errors.

Preventive Measures

To prevent future occurrences of TSDB corruption, consider implementing the following measures:

Ensure regular backups of your Prometheus data. Use reliable storage solutions and monitor disk health. Gracefully shut down the Prometheus server to avoid abrupt terminations.

For more detailed information on Prometheus and TSDB management, you can refer to the Prometheus Documentation and the TSDB Storage Documentation.