= Parameter Reference
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== Cluster Parameters

`numShards`::
Defaults to `1`. The number of shards to hash documents to. There must be one leader per shard and each leader can have _N_ replicas.


== SolrCloud Instance Parameters

These are set in `solr.xml`, but by default the `host` and `hostContext` parameters are set up to also work with system properties.

`host`::
Defaults to the first local host address found. If the wrong host address is found automatically, you can override the host address with this parameter.

`hostPort`::
Defaults to the port specified via `bin/solr -p <port>`, or `8983` if not specified. The port that Solr is running on. This value is only used when `-DzkRun` is specified without a value (see below), to calculate the default port on which embedded ZooKeeper will run. In the `solr.xml` shipped with Solr, the `hostPort` system property is not referenced, and so is ignored. If you want to run Solr on a non-default port, use `bin/solr -p <port>` rather than specifying `-DhostPort`.

`hostContext`::
Defaults to `solr`. The context path for the Solr web application.

== SolrCloud Instance ZooKeeper Parameters

`zkRun`::
Defaults to `localhost:<hostPort+1000>`. Causes Solr to run an embedded version of ZooKeeper. Set to the address of ZooKeeper on this node; this allows us to know who you are in the list of addresses in the `zkHost` connect string. Use `-DzkRun` (with no value) to get the default value.

`zkHost`::
The host address for ZooKeeper. Usually this is a comma-separated list of addresses to each node in your ZooKeeper ensemble.

`zkClientTimeout`::
Defaults to 15000. The time a client is allowed to not talk to ZooKeeper before its session expires.

`zkRun` and `zkHost` are set up using system properties. `zkClientTimeout` is set up in `solr.xml` by default, but can also be set using a system property.

== SolrCloud Core Parameters

`shard`::
Defaults to being automatically assigned based on numShards. Specifies which shard this core acts as a replica of. `shard` can be specified in the <<defining-core-properties.adoc#defining-core-properties,`core.properties`>> for each core.

Additional cloud related parameters are discussed in <<format-of-solr-xml.adoc#format-of-solr-xml,Format of solr.xml>>
