1. A frugal cloud file server apparatus in a frugal cloud file architecture including a plurality of disparate storage systems for storing a file image including a plurality of file image blocks, the apparatus comprising: a data storage; and a processor communicatively coupled to the data storage, the processor configured to: maintain, in the data storage, a first set of file block locations of at least a portion of the plurality of file image blocks that are located in a first storage system of the plurality of disparate storage systems; and maintain, in the data storage, a second set of file block locations of blocks that are located in a second disparate storage system of the plurality of disparate storage systems; wherein at least a plurality of in-use file blocks corresponding to the second set of file block locations are maintained in the second disparate storage system based on a plurality of eviction times corresponding to the plurality of in-use blocks.