A file storage system is implemented by coordinating non-exhaustible and exhaustible storage devices. The exhaustible storage devices include lower grade flash based storage devices. The non-exhaustible storage devices are based on magnetic recording mechanisms or higher grade flash storage. The file storage system stores received content items on the exhaustible storage devices, and stores metadata for the content items and/or the file storage system on the non-exhaustible storage devices. During operation, the file storage system globally optimizes the content items on the exhaustible storage devices such that more heavily accessed items are moved to exhaustible storage devices that have experienced relatively few data operations. The file storage system moves less frequently accessed content items to exhaustible storage devices that have experienced a relatively large number of data operations. As such, the operation lifetime of the exhaustible storage devices as a whole can be prolonged.