Storage tier with compressed forward map

A method comprising:

• generating a forward map for a storage tier, the forward map mapping a plurality of logical block addresses to physical locations on the storage tier;
• compressing the forward map;
• receiving a request from a host to modify a mapping of a logical block address to a physical location on the dynamic storage tier in the forward map;
• updating a superseding data structure in response to the request from the host;
• decompressing at least a portion of the forward map;
• sifting at least a portion of the forward map;
• and
• recompressing at least a portion of the forward map.

A data storage device comprising:

• a storage tier;
• a storage controller operably coupled to the storage tier and configured to be communicatively coupled to a host device, the storage controller including:
• a first memory operably coupled to the storage controller and configured to store a superseding data structure;
• a second memory operably coupled to the storage controller and configured to store a forward map, the forward map configured to map a plurality of logical block addresses to physical locations on the storage tier;
• a sifting module configured to sift the forward map based on data contained in the superseding data structure;
• and
• a compression module configured to compress the forward map, to generate a compressed forward map.