Elasticsearch NoSuchSnapshotException: No such snapshot

Brief Explanation

The "NoSuchSnapshotException: No such snapshot" error occurs in Elasticsearch when attempting to access or restore a snapshot that does not exist or is not accessible in the specified repository.

Common Causes

1. The snapshot name provided is incorrect or misspelled.
2. The snapshot has been deleted or has expired.
3. The repository configuration is incorrect or has changed.
4. Permissions issues preventing access to the snapshot repository.
5. Network or connectivity problems between Elasticsearch and the snapshot repository.

Troubleshooting and Resolution Steps

1. Verify the snapshot name:

   • Use the GET /_snapshot/<repository>/_all API to list all available snapshots in the repository.
   • Ensure the snapshot name in your request matches exactly with an existing snapshot.

2. Check repository configuration:

   • Review the repository settings using GET /_snapshot/<repository> API.
   • Verify that the repository path and other settings are correct.

3. Inspect permissions:

   • Ensure the Elasticsearch process has read access to the snapshot repository.
   • Check file system permissions if using a shared file system repository.

4. Verify repository connectivity:

   • For remote repositories (e.g., S3), check network connectivity and authentication.
   • Use the POST /_snapshot/<repository>/_verify API to validate the repository configuration.

5. Review snapshot lifecycle policies:

   • If using Index Lifecycle Management (ILM), check if snapshots are being automatically deleted.

6. Recreate the snapshot:

   • If the snapshot is missing and cannot be recovered, consider creating a new snapshot of the required data.

Additional Information and Best Practices

• Regularly monitor and maintain your snapshot repository to ensure snapshots are created and retained as expected.
• Implement a naming convention for snapshots to easily identify their contents and creation date.
• Use the Snapshot Lifecycle Management (SLM) feature to automate snapshot creation and deletion.
• Keep your Elasticsearch and repository plugin versions compatible to avoid compatibility issues.
• Document your snapshot and restore procedures for quick reference during emergencies.

Frequently Asked Questions

Q1: How can I list all available snapshots in a repository?

A1: Use the GET /_snapshot/<repository>/_all API to retrieve a list of all snapshots in a specific repository.

Q2: Can I restore a partial snapshot if the full snapshot is not available?

A2: Yes, you can restore specific indices from a snapshot using the indices parameter in the restore API, provided those indices are present in the available snapshot.

Q3: What should I do if my snapshot repository becomes corrupted?

A3: First, try to verify the repository using the POST /_snapshot/<repository>/_verify API. If issues persist, you may need to recreate the repository and take new snapshots of your data.

Q4: How often should I take snapshots of my Elasticsearch cluster?

A4: The frequency depends on your data change rate and recovery point objective (RPO). Common practices include daily snapshots for slowly changing data and more frequent snapshots (e.g., hourly) for rapidly changing data.

Q5: Can I rename a snapshot after it's been created?

A5: Elasticsearch does not provide a direct way to rename snapshots. Instead, you would need to restore the data from the existing snapshot and create a new snapshot with the desired name.