Embodiments of the invention include systems and methods for auto-tiering multiple file systems across a common resource pool. Storage resources are allocated as a sub-LUN auto-tiering (SLAT) sub-pool. The sub-pool is managed as a single virtual address space (VAS) with a virtual block address (VBA) for each logical block address of each data block in the sub-pool, and a portion of those VBAs can be allocated to each of a number of file systems. Mappings are maintained between each logical block address in which file system data is physically stored and a VBA in the file system's portion of the virtual address space. As data moves (e.g., is added, auto-tiered, etc.), the mappings can be updated. In this way, multiple SLAT file systems can exploit the full resources of the common SLAT sub-pool and maximize the resource options available to auto-tiering functions.