### Understand the alert

This alert monitors the `corruption_errs` metric in the `btrfs.device_errors` chart. If you receive this alert, it means that your system's BTRFS file system has encountered one or more corruption errors in the past 10 minutes. These errors indicate data inconsistencies on the file system that could lead to data loss or other issues.

### What are BTRFS corruption errors?

BTRFS (B-Tree File System) is a modern, fault-tolerant, and highly scalable file system used in several Linux distributions. Corruption errors in a BTRFS file system refer to inconsistencies in the data structures that the file system relies on to store and manage data. Such inconsistencies can stem from software bugs, hardware failures, or other causes.

### Troubleshoot the alert

1. Check for system messages:

   Review your system's kernel message log (`dmesg` output) for any BTRFS-related errors or warnings. These messages can provide insights into the cause of the corruption and help you diagnose the issue.

   ```
   dmesg | grep -i btrfs
   ```
   
2. Run a file system check:

   Use the `btrfs scrub` command to scan the file system for inconsistencies and attempt to automatically repair them. Note that this command may take a long time to complete, depending on the size of your BTRFS file system.

   ```
   sudo btrfs scrub start /path/to/btrfs/mountpoint
   ```

   After the scrub finishes, check the status with:

   ```
   sudo btrfs scrub status /path/to/btrfs/mountpoint
   ```

3. Assess your storage hardware

   In some cases, BTRFS corruption errors may be caused by failing storage devices, such as a disk drive nearing the end of its lifetime. Check the S.M.A.R.T. status of your disks using the `smartctl` tool to identify potential hardware issues.

   ```
   sudo smartctl -a /dev/sdX
   ```

   Replace `/dev/sdX` with the actual device path of your disk.

4. Update your system

   Ensuring that your system has the latest kernel, BTRFS tools package, and other relevant updates can help prevent software-related corruption errors.

   For example, on Ubuntu or Debian-based systems, you can update with:

   ```
   sudo apt-get update
   sudo apt-get upgrade
   ```

5. Backup essential data

   As file system corruption might result in data loss, ensure that you have proper backups of any critical data stored on your BTRFS file system. Regularly back up your data to an external or secondary storage device.

