Sandisk Technologies Inc.

Nicholas Thomas

Alan Welsh Sinclair

Barry Wright

Abhijeet Manohar

Daniel Edward Tuers

Yehuda Hahn

Joseph Robert Meza

Michael Anthony Moser

Marina Frid

Igor Genshaft

Jonathan Hsu

Oleg Kragel

Vered Kelner

Raja Alwar Gopinath

A non-volatile memory system may include a write task queue that queues write commands and a garbage collection module that analyzes information about pending write commands in the write task queue in order to perform garbage collection. Based on its analysis of the write task queue, the garbage collection module performs discouraging actions to discourage itself from selecting certain blocks in a candidate list to be source blocks for garbage collection. In addition or alternatively, the garbage collection module performs encouraging actions to encourage itself to select blocks storing current valid data associated with a write command as source blocks for garbage collection. Write amplification may be reduced as a result of the discouraging and encouraging actions.

Garbage collection based on queued and/or selected write commands

A cluster association recognition system and related method are described. The system may identify sequences of data clusters in compilations of cluster journals. The system may generate the compilations by populating the cluster journals with cluster identifications associated with host addresses identified in host read requests. Upon receipt of future read requests, the cluster sequences may be used to identify data sets that are associated with a cluster sequence in order to identify further data sets that a host is likely to request.

Self-describing cluster association

A memory system and method for reducing read disturb errors are disclosed. In one embodiment, a memory system is provided comprising a plurality of blocks of memory and a controller. The controller is configured to detect a read disturb error in a block, identify data that caused the read disturb error, and move the data that caused the read disturb error to a block with a higher read endurance. This can be done by assigning read counters to blocks to determine frequently-read data, and storing that data in a separate block until it is less frequently read and will likely not cause additional read disturb errors.

Memory system and method for reducing read disturb errors

Methods and systems for managing data storage in a non-volatile memory system are disclosed. The method may include receiving data, determining a data classification for the received data from a predetermined plurality of data classifications, writing the received data to an open block having only data of a same data classification as the determined data classification and, upon completely programming the open block, associating an epoch indicator where the epoch indicator defines a time period within which the block was created. When a block reclaim trigger is detected, only data within a same data classification and epoch may be reclaimed. An incrementing epoch indicator identifies a predetermined time granularity and is assigned to data such that earlier data and newer data are distinguishable. A system to implement the method may include a non-volatile memory and a controller configured to track and apply epoch and data-type classification information for data.

Method and system for managing data in non-volatile memory

A system and method is disclosed for tracking block mapping overhead in a non-volatile memory. The system may include a non-volatile memory having multiple memory blocks and a processor configured to track a block level mapping overhead for closed blocks of the multiple memory blocks. The processor may be configured to track predetermined logical address ranges within which data written to a block fall, and then store the sum of the number of different logical address ranges for each respective block as a block address entropy metric. The method may include the processor using the block address entropy metric to select source blocks for garbage collection with a lower block address entropy metric or to adjust other operational characteristics such as data routing within the non-volatile memory system based on average block address entropy for a group of blocks.

System and method for tracking block level mapping overhead in a non-volatile memory

A system and method for compacting data in a non-volatile memory system that may reduce the need for control data updates is described. The method may include copying valid data from a source block to a destination block, and also writing new host data to the destination block, such that the offset position in the destination block of the copied data is the same as in the source block and fewer mapping table updates are needed for the copied data. The system may include a non-volatile memory system with a coarse granularity mapping table and a fine granularity mapping table where a controller in the non-volatile memory system is configured to only update the coarse granularity mapping table for compacted data written to a new block, but is configured to update both the fine and coarse granularity mapping tables for new host data written to the new block.

Method and system for compacting data in non-volatile memory

A mass storage memory system and method of operation are disclosed. The memory system includes an interface adapted to receive data from a host system, a plurality of memory die and a controller, where the controller is configured to read or write data synchronously across a plurality of die connected to different channels based on a first command, and to read or write data asynchronously and independently in different die in the same channel based on a second command. The controller may program data in a maximum unit of programming for a single memory die. The controller may be a plurality of controllers each configured to select which die of an exclusive subset of die to write data based on characteristics of the die in the subset. The plurality of die may be multi-layer, and multi-partition per layer, flash memory die.

Method and system for asynchronous die operations in a non-volatile memory

A multi-layer memory and method for performing background maintenance operations are disclosed. The memory includes a plurality of flash memory die having multiple layers, where each layer is made up of flash memory cells having a greater bit per cell storage capacity than then prior layer and each layer may have a plurality of partitions for different data types. A controller managing the flash memory die is configured to identify an idle die and determine if a layer in the die satisfies a background maintenance criterion. Upon identifying a layer satisfying the background maintenance criterion, the valid data from reclaim blocks in the layer is relocated into a relocation block in the same layer until the relocation block is filled and the background maintenance cycle ends.

Method and system for managing background operations in a multi-layer memory

A data storage device includes a controller coupled to multiple groups of data storage dies, such as a meta-meta-die. The controller is configured to write data to a first meta-block if a storage size associated with a first group of data storage dies associated with a first priority is greater than or equal to a threshold storage size. The first meta-block includes a respective block of each data storage die of the first group. The controller is further configured to write the data to a second meta-block if the storage size associated with the first group is less than the threshold storage size. The second meta-block includes a respective block of each data storage die of the first group and further includes a respective block of each data storage die of the second group. Each data storage die of the second group is associated with a second priority.

Storage region mapping for a data storage device

A multi-layer memory and method for operation is disclosed. The memory includes multiple layers, where each layer includes flash memory cells having a greater bit per cell capacity than the prior layer and each layer may include a plurality of partitions having blocks exclusively associated with a particular data type. The method may include directing host data directly into a particular partition of a particular layer of the multi-layer memory upon receipt depending on a type of the data. The method may also include copying data within the same partition in a respective layer in a data relocation operation to generate more free blocks of memory so that data preferably stays within each layer and in the same partition, as well as transferring data from one layer to the next higher bit per cell layer within a same partition when layer transfer criteria are met.

Multi-layer non-volatile memory system having multiple partitions in a layer

A method and system are disclosed for handling logical-to-physical mapping in a storage device. The method includes the storage device storing in fast access memory, such as DRAM, only a fixed-size subset of the primary mapping table in non-volatile memory, along with contiguity information of physical addresses for logical address not in the subset that are adjacent to the logical addresses in the subset. The system includes a storage device having volatile memory, non-volatile memory and a controller in communication with the volatile and non-volatile memory that is configured to carry out the method noted above.

Method and system for creating a mapping table cache from an interleaved subset of contiguous mapping data for a storage device

A multi-later memory and method for operation is disclosed. The memory includes at least one flash memory die having multiple layers and a controller configured to execute block reclaim operations in a layer of the flash memory die until a net gain of at least one additional free block has been made in the layer. The method may include relocating data from reclaim blocks to relocation blocks within the same layer, or within a same partition in the same layer until a net gain of one free block has been achieved and an integer number of relocation blocks has been filled with relocated data. The method may also include moving data from reclaim blocks in a first layer into destination blocks in a second layer until a net gain of at least one free block has been achieved in the first layer.

Method and system for managing block reclaim operations in a multi-layer memory

A system and method for managing program cycles in a multi-layer memory are disclosed. The method includes a controller receiving a request to program data from a host and, in advance of programming data associated with the request, determining a program cycle for programming the data associated with the request. The programming cycle may be a set of a host data write programming operation and any maintenance programming operations on an amount of data already programmed in the plurality of memory layers that is necessary to provide free memory capacity for a subsequent request to program data from the host. The controller programs the data associated with the host request, and the amount of data to be programmed in maintenance operations, in predetermined programming units according to the determined program cycle.

Method and system for managing program cycles including maintenance programming operations in a multi-layer memory

A system and method for I/O optimization in a multi-queued environment are provided. In one embodiment, a host is provided that sorts commands into a plurality of queues, wherein a command is sorted based on its data characteristic. The host receives a read request from a storage module for commands in the plurality of queues and provides the storage module with the requested commands. In another embodiment, a storage module is provided that processes commands from a host based on the data characteristic of the queue that stored the command on the host. In another embodiment, a storage module sorts command completions into a plurality of queues, wherein a command completion is sorted based on its resulting status code.

System and method for I/O optimization in a multi-queued environment

A flash memory system having unequal number of memory die and method for operation are disclosed. The memory system includes a plurality of flash memory die distributed unevenly among different control lines, such that there are an unequal number of die between control lines. A total physical capacity of the plurality of flash memory die is greater than a total logical capacity such that the memory system is over provisioned with physical capacity. A logical address splitter directs data received from a host system and associated with host logical block addresses such that each control line only receives data associated with predetermined host logical block address ranges and directs the data such that a ratio of physical capacity to logical capacity is equal among each of the control lines, regardless of the different number of die and associated different physical capacity per control line.

Growing community of inventors

Dundee, United Kingdom

Nicholas Thomas