With Solr 4.x, http://localhost:8983/solr/admin/cores returns an XML description of loaded cores, which indicates the file path location of the instanceDir
.
...
<lst name="collection1">
<str name="name">collection1</str>
<bool name="isDefaultCore">true</bool>
<str name="instanceDir">C:\solr\solr-4.10.1\example\solr\collection1\</str>
...
On my Windows 7 PC, this is presented as a full path, but others have reported this as relative path. What factors can cause this value to be presented as a relative path, and is there a way to force this to be presented as a full path?