# Migrating Cluster Data

You can migrate data from one cluster to another. In certain scenarios, for example, if you cannot get sufficient capacity by changing the specifications of the current cluster, you can create a cluster of higher specifications and migrate all data of the current cluster to the new one. Alternatively, you can merge indices in two clusters to one cluster to meet your business needs. CSS enables you to migrate cluster data by using the index backup and restoration function, specifically, by restoring the snapshot of a cluster to the target cluster.

#### Prerequisites

- The source and target clusters are in the same region.
- The version of the target cluster is the same as or later than that of the source cluster.
- The number of nodes in the target cluster must be greater than half of the number of nodes in the source cluster.

#### Suggestions

- The number of nodes in the target cluster should be no less than the number of replicas in the source cluster.
- The CPU, memory, and disk configurations of the target cluster should be no less than those of the source cluster. This will minimize service loss after migration.

In this section, assume that data of cluster Es-1 is migrated to cluster Es-2. Cluster Es-2 runs a version later than that of cluster Es-1 and the number of nodes in cluster Es-2 is greater than half of that in cluster Es-1.

#### Procedure

1. On the Clusters page, click Es-1. On the displayed page, click Cluster Snapshots.
2. Click Create Snapshot to manually create a snapshot. In the displayed dialog box, enter the snapshot name and click OK.

   If you use the index backup and restoration function for the first time, you need to perform basic configurations first. For more details, see Manually Creating a Snapshot.

   Figure 1 Creating a snapshot
3. In the snapshot list, locate the row that contains the target snapshot and click Restore in the Operation column to restore data to cluster Es-2.
   - Leave the Index option blank (default setting), indicating that you want to restore data of all indices in cluster Es-1.
   - From the Cluster drop-down list, select Es-2.

   Click OK. You can also rename the restored index.

   Figure 2 Restoring a snapshot
4. After restoration is complete, data in cluster Es-1 will be migrated to cluster Es-2.

Parent topic: Managing Elasticsearch Clusters