Methods and systems for preserving blocks that are neither obsolete nor cold
AssigneeNimble Storage, Inc.
InventorUmesh Maheshwari
Life of this patent
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Abstract
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.
Claims20
A method for a flash cache that stores a first group of one or more segments and a second group of one or more segments, each segment storing zero or more blocks, the method comprising:
- for the first group of one or more segments, determining which blocks are obsolete, and which blocks are cold, wherein obsolete blocks will no longer be accessed, and cold blocks will not likely be accessed;
- and
- copying, from the first group of one or more segments to the second group of one or more segments, all blocks that are neither obsolete nor cold, wherein at least one block from the first group of one or more segments is neither obsolete nor cold.
A storage system, comprising (i) a flash cache that stores a first group of one or more segments and a second group of one or more segments, each segment storing zero or more blocks, and (ii) a controller communicatively coupled to the flash cache, wherein the controller is configured to:
- for the first group of one or more segments, determine which blocks are obsolete, and which blocks are cold, wherein obsolete blocks will no longer be accessed, and cold blocks will not likely be accessed;
- and
- copy, from the first group of one or more segments to the second group of one or more segments, all blocks that are neither obsolete nor cold, wherein at least one block from the first group of one or more segments is neither obsolete nor cold.
Dependencies are inferred from the claim text.