A lightweight filesystem may be provided for remote storage caching. A filesystem may maintain a persistent cache for a data set stored as data files in immutable data objects in a remote data store. Filesystem metadata may be evaluated to determine whether a portion of a data file is stored in the persistent cache according to an offset and length specified in a request. If in the persistent cache, data obtained from a data block in the persistent cache may be returned. If not in the persistent cache, then the remote data store may be accessed and the data file in the immutable data object read to obtain the portion of the data file.