Apparatus, system, and method for solid-state storage as cache for high-capacity, non-volatile storage

A non-transitory computer-readable storage medium comprising instructions to cause a computing device to perform a method, the method comprising:

• caching data of a primary storage system on a cache comprising a solid-state storage medium in response to storage requests directed to the primary storage system, wherein the cached data corresponds to respective identifiers of the primary storage system, and wherein caching the data of the primary storage system comprises,
• storing the data of the primary storage system at respective physical addresses of the solid-state storage medium, and
• maintaining entries in a logical-to-physical translation index, the entries associating identifiers corresponding to cached data of the primary storage system with respective physical addresses at which the cached data is stored on the solid-state storage medium;
• servicing a read request pertaining to a specified identifier of the primary storage system, wherein servicing the read request comprises,
• identifying an entry of the logical-to-physical translation index for the specified identifier of the primary storage system,
• using the identified entry to determine a physical address at which cached data of the specified identifier is stored on the solid-state storage medium, and
• retrieving the cached data of the specified identifier from the solid-state storage medium at the determined physical address;
• and
• modifying the particular entry of the logical-to-physical translation index to associate the specified identifier with a different physical address of the solid-state storage medium in response to moving the cached data of the specified identifier to the different physical address on the solid-state storage medium, wherein the particular entry is modified while retaining the particular entry in the logical-to-physical translation index, and while retaining the cached data of the specified logical identifier in the cache.

An apparatus comprising:

• a storage controller configured to write data to respective storage locations of a solid-state storage device;
• an index module configured to maintain a logical-to-physical translation index comprising entries that associate logical addresses of data stored on the solid-state storage device with respective storage locations of the solid-state storage device:
• a cache module configured to cache data of a high-capacity storage system in a cache on the solid-state storage device by use of the storage controller, wherein to cache data associated with a specified logical address of the high-capacity storage system, the storage controller writes the data to a first storage location on the solid-state storage device and the index module associates the specified logical address of the high-capacity storage system with the first storage location in a designated entry of the logical-to-physical mapping index;
• wherein the cache module is further configured to service an access request pertaining to the specified logical address of the high-capacity storage system, wherein to service the data request the cache module determines that the specified logical address is stored in the cache on the solid-state storage device based on identifying the designated entry in the logical-to-physical mapping index, and the storage controller reads the first storage location of the solid-state storage device associated with the specified logical address by the designated entry,
• wherein the index module is configured to alter the designated entry of the logical-to-physical mapping index in response to the storage controller relocating the data stored on the first storage location to a second storage location on the solid-state storage device, wherein the index module alters the designated entry to associate the specified logical address of the high-capacity storage system with the second storage location on the solid-state storage device while maintaining the designated entry in the logical-to-physical translation index such that the data of the specified logical address is retained in the cache on the solid-state storage device while the designated entry is altered.