The index directory is the place where all index and configuration files are stored. It is in read/write mode during the import, modify and build processes and read mode during search. When in read/write mode, the import/build operations work on temporary files to allow concurrent search operations to continue unaffected.
The index directory can reside in any location (provided the user process has permission to access it). The index configuration itself has no absolute paths, so it is portable. The index directory has references to other resources, (such as database files, dictionaries, plug-in DLLs and folder paths) which can be set with paths relative to the index directory, using relative paths allows the index and the resources to be moved easily to other locations as a unit.
The only resources linked from an index that must be absolute, are document URLs - see the "Typical Development & Deployment Scenarios" section under "Examples" if the index contains links to 'localhost'.
Of course, for read/write operations (import/build/modify) the user process must have read/write access, and for read operations (search) the user must at least have read access.
The user names under which the process runs are typically;
The index configuration is stored in the "configuration.xml file in the index directory - please see the Configuration section for more information.