This directory is the default Solr home directory which holds configuration files and Solr indexes (called cores).
The Solr Home directory typically contains the following...
This is the primary configuration file Solr looks for when starting; it specifies high-level configuration options that apply to all of your Solr cores, such as cluster-wide SolrCloud settings like the ZooKeeper client timeout.
In addition, you can also declare Solr cores in this file, however it is recommended to just use automatic core discovery instead of listing cores in solr.xml.
If no solr.xml file is found, then Solr assumes that there should be a single SolrCore named “collection1” and that the “Instance Directory” for collection1 should be the same as the Solr Home Directory.
For more information about solr.xml, please see: https://lucene.apache.org/solr/guide/solr-cores-and-solr-xml.html
Although solr.xml can be configured to look for SolrCore Instance Directories in any path, simple sub-directories of the Solr Home Dir using relative paths are common for many installations.
During startup, Solr will scan sub-directories of Solr home looking for a specific file named core.properties. If core.properties is found in a sub-directory (at any depth), Solr will initialize a core using the properties defined in core.properties. For an example of core.properties, please see:
example/solr/collection1/core.properties
For more information about core discovery, please see:
https://lucene.apache.org/solr/guide/defining-core-properties.html
Although solr.xml can be configured with an optional “sharedLib” attribute that can point to any path, it is common to use a “./lib” sub-directory of the Solr Home Directory.
When using SolrCloud using the embedded ZooKeeper option for Solr, it is common to have a “zoo.cfg” file and “zoo_data” directories in the Solr Home Directory. Please see the SolrCloud documentation for more details.