# Replicas

The number of identical copies of each document to index.

The number of copies (that is, the value of `Replicas` plus one) must be smaller than the number of child servers. If you create more copies than there are child servers, Distributed Index Handler does not start.

In consistent hashing mode, content is distributed between virtual nodes, which the Distributed Index Handler assigns to its child servers. When you configure replicas, DIH copies the documents in a particular virtual node to two or more child servers.

This method ensures there are two mirrored copies of the document in your system without you having to set up specifically mirrored child servers.

When you configure replicas, you must configure your DAH in simple combinator mode, and combine query results by reference.

NOTE: You cannot change the number of replicas in your system. If you want to change this number, you must use a clean DIH installation and reindex all your content.

When you send a `GetQueryTagValues` to the DAH in a system that uses replicas, the document counts for tags includes a value for each copy of the document that exists (that is, it counts each replica as a separate document).

Type: | Long
Default: | 0
Required: | No
Configuration Section: | ConsistentHashing
Example: | `Replicas=1`
See Also: | UseConsistentHashing

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