Reclaiming segments in flash memory

摘要

A storage device made up of multiple storage media is configured such that one such media serves as a cache for data stored on another of such media. The device includes a controller configured to manage the cache by consolidating information concerning obsolete data stored in the cache with information concerning data no longer desired to be stored in the cache, and erase segments of the cache containing one or more of the blocks of obsolete data and the blocks of data that are no longer desired to be stored in the cache to produce reclaimed segments of the cache.

主权项

1. A method for a storage device comprising a flash memory and a controller, the flash memory (i) communicatively coupled to the controller and (ii) storing a group of segments, each of the segments from the group of segments including a plurality of blocks, the method comprising:
for each of the segments from the group of segments, computing by the controller a reclamation metric by summing a number of cold blocks present in the segment with a number of obsolete blocks present in the segment, wherein the cold blocks are less likely to be accessed and the obsolete blocks will no longer be accessed; identifying by the controller one or more of the segments from the group of segments as candidate segments for reclamation based on the reclamation metric corresponding to each of the segments from the group of segments; and reclaiming by the controller one or more of the candidate segments resulting in one or more reclaimed segments.