# Run the Distributed Index Handler in Non-Mirror Mode

In non-mirror mode the DIH distributes the index data that it receives evenly across the connected IDOL Servers.

Run the DIH in non-mirror mode if the amount of data to index is too large for a single IDOL Server. This option can reduce the index process time, particularly if the IDOL Servers that the DIH indexes into are on different machines.

The DIH periodically checks if all the connected IDOL Servers are operating. The behavior when a child server fails depends on your configuration:

- In simple non-mirror distribution modes, the DIH treats any IDOL Server that fails as `UpdateOnly`. While the child server is down, DIH queues any updates to existing documents, but distributes new content between the remaining child servers. This behavior ensures that all content is indexed into the available servers, but that document updates and deduplication occurs in the offline child server when it comes back online.

- In advanced distribution modes (see Manage the Indexing Process), the DIH queues the data that this IDOL Server normally receives, and when the IDOL Server starts operating again, it indexes the queued data into it.

To run the DIH in non-mirror mode

1. Open the DIH configuration file in a text editor.

2. In the `[Server]` section, find the `MirrorMode` setting and set it to `False`.

3. Save and close the configuration file.

4. Restart the DIH for your changes to take effect.

NOTE: When you change the `MirrorMode` configuration option to enable or disable mirror mode, you must also delete the `Main/` subdirectory in the DIH installation directory.

This additional action prevents accidentally switching between mirror and non-mirror mode, which can cause a loss of data. If you do not delete the `Main/` directory when you change the `MirrorMode` option, DIH does not start.

In non-mirror mode, you can choose various data distribution configurations.

- By default, the DIH distributes data as soon as it receives the data. To send documents in batches, set the `DistributeOnBatch` configuration parameter (in the [`Server]` section of the DIH configuration file) to `True`. This option can improve indexing speed, although the distribution of data among child servers can be more uneven.

- By default, the DIH sends all index data to all child servers. To send the full document only to the child server that must index the content, set the `DistributeSendMinimal` configuration parameter. For more information, see Send Minimal Documents.

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