Overview

This guide will help you to set up and enable regular backups of your Elasticsearch index without causing downtime. Backing up Elasticsearch indices is particularly beneficial for use cases where the data on Swarm is static, like Write Once Read Many (WORM). However, it is still necessary to perform a “Refresh Search Index” operation after recovery to ensure the Elasticsearch index is fully updated and synchronized. This process is crucial because it catches up the Elasticsearch index with the latest data state.

For use cases with frequent updates, such as backup software like Commvault, NetBackup, Veeam et al, restoring an Elasticsearch index from backup is not suitable. After restoring a specific point-in-time of the Elasticsearch index, the backup client software may not be able to read the data beyond that time. To address this, a “Refresh Search Index” is required. This synchronizes the Elasticsearch Index with the current state of data in the storage cluster. This refresh process can take almost the same amount of time as creating a new search feed, which is why recovery of Elasticsearch from backup is less beneficial for these use cases.

Prerequisites

• Elasticsearch cluster running.

• Shared file system accessible by all Elasticsearch nodes.

• Access to the cluster via curl or a similar HTTP client.

• (Optional) Elasticsearch Curator for automating snapshots.

Step-by-Step Guide

1. Create a Snapshot Repository

   You need to create a snapshot repository where the snapshots will be stored. This can be a shared file system or an S3 bucket.
   Using a Shared File System:
   First, specify the shared repository location in the elasticsearch.yml file:

   path.repo: "/mount/backups/my_backup"

   Then, create the repository using the following command:

   curl -X PUT "http://<es_node_ip>:9200/_snapshot/my_backup" -H 'Content-Type: application/json' -d' { "type": "fs", "settings": { "location": "/mount/backups/my_backup" } }'

   Using DataCore Swarm S3 bucket:
   When the target repository is another Swarm cluster, the command to create the snapshot repository would be as follows:

   curl -X PUT "http://<es_node_ip>:9200/_snapshot/my_s3_backup" -H 'Content-Type: application/json' -d' { "type": "s3", "settings": { "bucket": "my-elasticsearch-backup-bucket", "endpoint": "https://datacore-swarm.example.com", "access_key": "your_access_key", "secret_key": "your_secret_key", "protocol": "https" } }'

2. Verify the Repository

   After creating the repository, verify it to ensure it is set up correctly:

3. Create a Snapshot

   Once the repository is set up and verified, create a snapshot of your index. Replace index_mumbkctcomobs.datacore.com.com0 with your index name.

4. Automate Snapshot Creation

   To automate the creation of snapshots, you can use cron jobs on Linux or scheduled tasks on Windows.

   Example using a cron job (runs daily at 2 AM):

5. Monitor Snapshots

   Regularly check the status of your snapshots to ensure they are completing successfully:

6. Restoring a Snapshot (if needed)
   If you need to restore a snapshot, you can do so with the following command:

   For the S3 bucket:

   • '"include_global_state": false' means that only the data stored in the particular index is restored.

   • If you wan to restore everything from the cluster, including templates, persistent cluster settings, and more, set '"include_global_state": true'.

Automating with Elasticsearch Curator

Elasticsearch Curator simplifies managing indices and snapshots. Here’s how to set it up:

1. Install Curator

2. Create a Curator Configuration File (curator.yml)

3. Create a Curator Action File (snapshot.yml)

    

4. Create a Cron Job to Run Curator

Best Practices

• Test Snapshots: Regularly restore snapshots to a test cluster to ensure data integrity.

• Monitor Resources: Monitor cluster resources during snapshot operations to ensure they do not impact performance.

• Automate Alerts: Set up alerts to notify you if a snapshot operation fails.

• Retention Policy: Implement a retention policy to manage storage, deleting older snapshots to save space.

By following these steps, you can enable regular backups of your Elasticsearch index without causing downtime, ensuring your data is safe and recoverable.