Graphite Carbon-cache not writing to disk

What is Graphite Carbon-cache not writing to disk

Understanding Graphite and Its Components

Graphite is a powerful monitoring tool used for storing and visualizing time-series data. It consists of three main components: Carbon, Whisper, and Graphite-web. Carbon is responsible for receiving metrics and storing them in the Whisper database. When Carbon-cache fails to write data to disk, it can disrupt the entire monitoring process.

Identifying the Symptom: Carbon-cache Not Writing to Disk

One common issue users encounter is that Carbon-cache appears to be running, but no data is being written to disk. This can manifest as missing data in your Graphite-web interface or logs indicating write failures.

Exploring the Root Cause

Disk Write Errors

Disk write errors can occur due to insufficient disk space, disk corruption, or permission issues. These errors prevent Carbon-cache from writing metrics to the Whisper database.

Configuration Issues

Misconfigurations in Carbon-cache settings can also lead to data not being written. This includes incorrect file paths, permissions, or syntax errors in the configuration files.

Steps to Resolve the Issue

Step 1: Check Disk Health

Ensure that your disk has enough space and is not corrupted. Use commands like df -h to check disk space and fsck to check for disk errors. Make sure the disk is mounted correctly and accessible.

Step 2: Review Carbon-cache Configuration

Examine the carbon.conf file, typically located in /opt/graphite/conf/. Ensure that the STORAGE_DIR and other paths are correctly set. Verify that the user running Carbon-cache has write permissions to these directories.

Step 3: Check Logs for Errors

Review the Carbon-cache logs for any error messages. These logs are usually found in /opt/graphite/storage/log/carbon-cache/. Look for messages indicating permission issues or disk write failures.

Step 4: Test Configuration Changes

After making changes, restart the Carbon-cache service to apply them. Use the command sudo service carbon-cache restart or systemctl restart carbon-cache depending on your system's init system.

Further Resources

For more detailed information on configuring and troubleshooting Graphite, refer to the official Graphite documentation. Additionally, community forums and resources like Stack Overflow can provide valuable insights and solutions from other users.