Apparatuses and methods related to command selection policy for electronic memory or storage are described. Commands to a memory controller may be prioritized based on a type of command, a timing of when one command was received relative to another command, a timing of when one command is ready to be issued to a memory device, or some combination of such factors. For instance, a memory controller may employ a first-ready, first-come, first-served (FRFCFS) policy in which certain types of commands (e.g., read commands) are prioritized over other types of commands (e.g., write commands). The policy may employ exceptions to such an FRFCFS policy based on dependencies or relationships among or between commands. An example can include inserting a command into a priority queue based on a category corresponding to respective commands, and iterating through a plurality of priority queues in order of priority to select a command to issue.

A method for mapping LUNs (logical unit numbers) in storage memory, performed by a storage system, is provided. The method includes determining a set of LUNs in the storage memory and generating a mapping from a logical address space to all of the LUNs in the set, based on the determining, so that each logical address in the logical address space maps to one LUN in the set. The method includes accessing one or more of the LUNs in accordance with the mapping.

A memory system includes a memory array having a plurality of memory cells; and a controller coupled to the memory array, the controller configured to: designate a storage mode for a target set of memory cells based on valid data in a source block, wherein the target set of memory cells are configured with a capacity to store up to a maximum number of bits per cell, and the storage mode is for dynamically configuring the target set of memory cells in as cache memory that stores a number of bits less per cell than the corresponding maximum capacity.

Converting RAID data between persistent storage types, including: for each portion of a RAID shard of a RAID stripe: writing, to a respective plurality of source solid state drives, the portion of the RAID shard; detecting that all portions of the RAID shard have been successfully written; copying, from one of the plurality of source solid state drives to a respective target solid state drive among a plurality of target solid state drives from one of the plurality of source solid state drives, the RAID shard, where the RAID shard is copied from a source solid state drive that is different from where each other RAID shard of the RAID stripe is copied from.

The present invention provides a control method of a flash memory controller, wherein the flash memory controller is configured to access a flash memory module, and the control method includes the steps of: receiving a settling command from a host device to configure a portion space of the flash memory module as a zoned namespace; receiving a write command from the host device to write data corresponding a first zone into a plurality of blocks of the flash memory module, wherein an access mode chose by the flash memory controller is determined based on a size of each zone and a size of each block.

A method, non-transitory computer readable medium, and device that assists with reducing memory fragmentation in solid state devices includes identifying an allocation area within an address range to write data from a cache. Next, the identified allocation area is determined for including previously stored data. The previously stored data is read from the identified allocation area when it is determined that the identified allocation area comprises previously stored data. Next, both the write data from the cache and the read previously stored data are written back into the identified allocation area sequentially through the address range.

In some examples, a system performs data deduplication using a deduplication fingerprint index in a hash data structure comprising a plurality of blocks, wherein a block of the plurality of blocks comprises fingerprints computed based on content of respective data values. The system merges, in a merge operation, updates for the deduplication fingerprint index to the hash data structure stored in a persistent storage. As part of the merge operation, the system mirrors the updates to a cached copy of the hash data structure in a cache memory, and updates, in an indirect block, information regarding locations of blocks in the cached copy of the hash data structure.

An apparatus to facilitate memory data compression is disclosed. The apparatus includes a memory and having a plurality of banks to store main data and metadata associated with the main data and a memory management unit (MMU) coupled to the plurality of banks to perform a hash function to compute indices into virtual address locations in memory for the main data and the metadata and adjust the metadata virtual address locations to store each adjusted metadata virtual address location in a bank storing the associated main data.

Embodiments of the invention describe a system main memory comprising two levels of memory that include cached subsets of system disk level storage. This main memory includes “near memory” comprising memory made of volatile memory, and “far memory” comprising volatile or nonvolatile memory storage that is larger and slower than the near memory.

The far memory is presented as “main memory” to the host OS while the near memory is a cache for the far memory that is transparent to the OS, thus appearing to the OS the same as prior art main memory solutions. The management of the two-level memory may be done by a combination of logic and modules executed via the host CPU. Near memory may be coupled to the host system CPU via high bandwidth, low latency means for efficient processing. Far memory may be coupled to the CPU via low bandwidth, high latency means.

According to the embodiments, an external storage device switches to an interface controller for supporting only a read operation of nonvolatile memory when a shift condition for shifting to a read only mode is met. A host device switches to an interface driver for supporting only the read operation of the nonvolatile memory when determining to recognize as read only memory based on information acquired from the external storage device.