# DREREDISTRIBUTE

Allows you to redistribute the index when you update the number or weight of child servers.

NOTE: This index action is only available for the DIH, and has no effect if you send it directly to IDOL Server.

In simple distribution mode, either with or without `DistributeSendMinimal`, you can remove a child Content engine or group and the DIH will automatically redistribute its documents among the remaining servers. You might want to do this if your index has reduced in size and you want to decommission a Content engine. To do this, run the action and use the `RemoveGroup` parameter to specify the ID of the Content engine or group to remove. The DIH does not index any more data into the specified engine, and its content is exported back to the DIH for redistribution. When redistribution is complete, the Content engine is removed from the DIH automatically, so you do not need to edit the configuration file.

Engine removal with redistribution of content is not available with mirror mode, distribute by reference, distribute by batch, distribute by date, or distribution by field values.

In consistent hashing mode, all content is distributed in virtual nodes, which the DIH assigns to one or more child servers. When you run the `DREREDISTRIBUTE` index action, DIH checks whether the child server architecture has changed. If there is a change, DIH automatically exports and indexes the content in virtual nodes to redistribute your data evenly between the available child servers.

When you have configured at least one document replica in your system, you can also use `DREREDISTRIBUTE` to rebuild a child server that has become unavailable (for example because of a hardware failure). In this case, you can use the EngineManagement action to change the host and port of the child server, and then you can use `DREREDISTRIBUTE` with the RebuildEngine parameter to rebuild the child server from replicas.

For more details about consistent hashing mode, refer to the DIH Administration Guide.

DIH can process only one `DREREDISTRIBUTE` index action at the same time. If it starts to process a second `DREREDISTRIBUTE` index action before all child servers have finished redistributing the content, the second `DREREDISTRIBUTE` returns the `Unavailable` error code and does not run.

NOTE: For this index action, DIH uses the IndexUID parameter to identify the export index actions that it sends to its child servers, and the index actions to generate to index the redistributed data. If you do not specify an IndexUID, DIH generates one automatically to track the redistribution.

## Example

    http://12.3.4.56:9071/DREREDISTRIBUTE

## Optional Parameters

This action accepts the following optional parameters.

Parameter | Description
--- | ---
DAHGSSServiceName | The GSSAPI service name of your DAH.
DAHHost | The host name or IP address of your DAH.
DAHPort | The ACI port of your DAH.
DAHSSLSectionName | The name of a section in the DIH configuration file that contains the SSL settings required to communicate with your DAH.
RebuildEngine | The IDs of child servers that you want to rebuild from replicas.
RemoveGroup | The ID of the child Content engine or group to remove.

This index action accepts the following standard index action parameters.

Parameter | Description
--- | ---
IgnoreMaxPendingItems | Whether to ignore the IndexQueueMaxPendingItems limit for this index action.
IndexUID | An identification code for any document tracking events.
NoArchive | Turn off configured archiving for the index action.
Priority | The priority for the index job.

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