Embodiments are directed to managing data in a file system. The file system that includes storage nodes that may be associated with storage volumes that may have a different capacity for storing data. A storage capacity of the file system may be determined based on a number of stripes of data that fit in the file system such that each stripe may be comprised of chunks that have a same chunk storage capacity. Slots in the file system that each match the chunk storage capacity may be determined based on the storage volumes. The chunks may be assigned to the slots in the file system based on the capacity of the storage nodes such that a number of chunks allocated to a same storage volume or a same storage node may be based on protection factor information.