Disclosed herein are systems, methods, and devices for testing deduplication repositories. Methods may include identifying a storage location based on a request for one or more data values associated with a read-only file system, where the read-only file system is a simulated file system, and where the storage location is identified based on a plurality of request parameters included in the request. The methods may also include generating, using a processor and responsive to the request, the one or more data values based on the plurality of request parameters and a plurality of configuration parameters, where the plurality of configuration parameters enable deterministic generation of all data values stored in the tile system. The methods may further include returning the one or more data values as a result of the request.