= Solr Configuration Files
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Solr has several configuration files that you will interact with during your implementation.

Many of these files are in XML format, although APIs that interact with configuration settings tend to accept JSON for programmatic access as needed.

== Solr Home
When Solr runs, it needs access to a home directory.

When you first install Solr, your home directory is `server/solr`. However, some examples may change this location (such as, if you run `bin/solr start -e cloud`, your home directory will be `example/cloud`).

The home directory contains important configuration information and is the place where Solr will store its index. The layout of the home directory will look a little different when you are running Solr in standalone mode vs. when you are running in SolrCloud mode.

The crucial parts of the Solr home directory are shown in these examples:

.Standalone Mode
[source,plain]
----
<solr-home-directory>/
   solr.xml
   core_name1/
      core.properties
      conf/
         solrconfig.xml
         managed-schema
      data/
   core_name2/
      core.properties
      conf/
         solrconfig.xml
         managed-schema
      data/
----

.SolrCloud Mode
[source,plain]
----
<solr-home-directory>/
   solr.xml
   core_name1/
      core.properties
      data/
   core_name2/
      core.properties
      data/
----

You may see other files, but the main ones you need to know are discussed in the next section.

== Configuration Files
Inside Solr's Home, you'll find these files:

* `solr.xml` specifies configuration options for your Solr server instance. For more information on `solr.xml` see <<solr-cores-and-solr-xml.adoc#solr-cores-and-solr-xml,Solr Cores and solr.xml>>.
* Per Solr Core:
** `core.properties` defines specific properties for each core such as its name, the collection the core belongs to, the location of the schema, and other parameters. For more details on `core.properties`, see the section <<defining-core-properties.adoc#defining-core-properties,Defining core.properties>>.
** `solrconfig.xml` controls high-level behavior. You can, for example, specify an alternate location for the data directory. For more information on `solrconfig.xml`, see <<configuring-solrconfig-xml.adoc#configuring-solrconfig-xml,Configuring solrconfig.xml>>.
** `managed-schema` (or `schema.xml` instead) describes the documents you will ask Solr to index. The Schema define a document as a collection of fields. You get to define both the field types and the fields themselves. Field type definitions are powerful and include information about how Solr processes incoming field values and query values. For more information on Solr Schemas, see <<documents-fields-and-schema-design.adoc#documents-fields-and-schema-design,Documents, Fields, and Schema Design>> and the <<schema-api.adoc#schema-api,Schema API>>.
** `data/` The directory containing the low level index files.

Note that the SolrCloud example does not include a `conf` directory for each Solr Core (so there is no `solrconfig.xml` or Schema file). This is because the configuration files usually found in the `conf` directory are stored in ZooKeeper so they can be propagated across the cluster.

If you are using SolrCloud with the embedded ZooKeeper instance, you may also see `zoo.cfg` and `zoo.data` which are ZooKeeper configuration and data files. However, if you are running your own ZooKeeper ensemble, you would supply your own ZooKeeper configuration file when you start it and the copies in Solr would be unused. For more information about SolrCloud, see the section <<solrcloud.adoc#solrcloud,SolrCloud>>.
