# Load Balancing Index Server Nodes

Applies to: File System Content Indexing, Office 365

To balance indexes across multiple nodes on an Index Server, you can run the load balancing operation. Load balancing moves indexes from one node to another node on the same Index Server to help distribute index data according to the capacity and resource availability of the nodes.

Load balancing is intended to help manage resource utilization as the data managed by an Index Server grows. For example, if an Index Server node approaches a critical resource condition, you can add a node and run the load balancing operation to redistribute indexes. Depending on the resource constraint, you might instead need to add resources, such as memory or disk capacity, or improve disk performance.

Important

Load balancing does not provide high availability (HA) or disaster recovery (DR). Adding multiple nodes to an Index Server and load balancing indexes between those nodes should not be considered an HA or DR configuration. For Index Server DR, see Office365 Index Server DR.

### How Load Balancing Works

When you run the load balancing operation, the Index Server evaluates whether indexes need to be moved between nodes. The operation considers the capacity and resource availability of the nodes, including factors such as available disk space, CPU resources and distribution and size of the indexes on the nodes.

Based on these conditions, the Index Server determines whether load balancing is required and which indexes should be moved.

Load balancing does not attempt to distribute index data equally across all nodes. Therefore, the amount of index data on each node might differ after a successful load balancing operation.

If the Index Server determines that the existing distribution does not require balancing, the operation does not move indexes. You do not need to add nodes or perform load balancing solely to achieve an equal distribution of index data.

To check the performance and health of the Index Server nodes, see Monitoring the Index Server. The Analytics - Low Disk Space alert can also be used to monitor the space available on the Index Server nodes. For more information, see Configuring Space Check for Index Server Cache.

## Before You Begin

- Verify that the Index Gateway package is installed on all of the nodes associated with the Index Server. By default, the Index Gateway package is automatically installed with the Index Store package.

- Create a backup plan and add it to the Index Server. The MediaAgent associated with the storage on the backup plan is used to stage the indexes that move from the source node to the destination node.

## Procedure

1. From the Command Center navigation pane, go to Manage > Infrastructure.

2. Click the Index servers tile.

3. In the Name column, click the Index Server.

4. On the Overview tab, in the Nodes section, click Load balance.

5. To specify the destination node, disable the Auto select destination node toggle key and then select the node from the Destination list.

   If you enable the Auto select destination node toggle key, then indexes are automatically balanced across the nodes based on the load balancing criteria.

6. Click Run.

## Result

To load balance the nodes, two jobs run: Autoscale Index Prepare and Autoscale Index Move. After the indexes are successfully moved to the destination node, the indexes are deleted from the source node.

If the Index Server determines that load balancing is not required based on the current node conditions, indexes are not moved.

## Related Topics

Adding a Node

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