Snapshots and Restores in Elasticsearch

Introduction

Snapshots and restores are essential features in Elasticsearch that help in backing up and recovering your data. Snapshots are incremental backups, which means they only store the data that has changed since the previous snapshot. This tutorial will guide you through the process of creating and restoring snapshots in Elasticsearch.

Setting Up a Snapshot Repository

Before you can take a snapshot, you need to register a snapshot repository. Elasticsearch supports various types of repositories, including shared file systems, Amazon S3, HDFS, and more. Here, we'll use a shared file system repository as an example.

{
  "type": "fs",
  "settings": {
    "location": "/mount/backups/my_backup",
    "compress": true
  }
}

This command registers a repository named my_backup that stores snapshots in the /mount/backups/my_backup directory on the shared file system.

Creating a Snapshot

Once the snapshot repository is set up, you can create a snapshot. You can take a snapshot of all indices or specific indices. Here is an example of taking a snapshot of all indices:

{
  "accepted": true
}

The wait_for_completion=true parameter ensures that the request will not return until the snapshot operation has completed. This is useful for testing and scripting purposes.

Viewing Snapshot Status

You can check the status of a snapshot to see if it's still running or if it has completed. The following command retrieves the status of the snapshot_1 snapshot in the my_backup repository:

{
  "snapshots": [
    {
      "snapshot": "snapshot_1",
      "repository": "my_backup",
      "uuid": "unique-identifier",
      "state": "SUCCESS",
      "start_time": "2023-10-01T12:00:00.000Z",
      "end_time": "2023-10-01T12:01:00.000Z",
      "duration_in_millis": 60000,
      "shards": {
        "total": 5,
        "failed": 0,
        "successful": 5
      }
    }
  ]
}

Restoring a Snapshot

Restoring a snapshot allows you to recover data from a backup. You can restore all indices or specific indices from a snapshot. Here is an example of restoring all indices from the snapshot_1 snapshot in the my_backup repository:

{
  "accepted": true
}

You can also restore specific indices by specifying them in the request body:

{
  "indices": "index_1,index_2",
  "ignore_unavailable": true,
  "include_global_state": false
}

The ignore_unavailable parameter allows the restore operation to proceed even if some of the indices are unavailable. The include_global_state parameter specifies whether to restore the global cluster state as part of the snapshot.

Conclusion

Snapshots and restores are powerful features in Elasticsearch that provide a robust backup and recovery mechanism. By following the steps outlined in this tutorial, you can easily create and restore snapshots to ensure the safety and integrity of your data.