Sandisk Corporation

Sandisk Technologies Inc.

Lexar Media, Inc.

Sandisk Corproation

Peter John Smith

Sergey Anatolievich Gorobets

Alan Welsh Sinclair

Alan David Bennett

Kevin M Conley

Robert Edwin Payne

Alan Douglas Bryce

Alan David Bennet

Philip D Royall

Techniques for managing data in a non-volatile memory system (e.g., Flash Memory) are disclosed. A controller can use information relating to a host's file system, which is stored by the host on non-volatile memory, to determine if one or more clusters (or sectors with clusters) are currently allocated. The controller can use the information relating to the host's file system to identify when the host is sending data to the next free cluster and to store such data in a sequential format by copying data from other locations in the non-volatile memory.

FAT analysis for optimized sequential cluster management

A memory unit has a busy control system that includes a busy control register that may be written by a controller. The contents of the busy control register determine whether a signal is sent from the memory unit to the controller and, if so, which of a plurality of signals is sent. A signal may automatically be sent from a selected memory unit and masked from an unselected unit.

Configurable ready/busy control

Host system data files are written directly to a large erase block flash memory system with a unique identification of each file and offsets of data within the file but without the use of any intermediate logical addresses or a virtual address space for the memory. Directory information of where the files are stored in the memory is maintained within the memory system by its controller, rather than by the host. The file based interface between the host and memory systems allows the memory system controller to utilize the data storage blocks within the memory with increased efficiency.

Direct file data programming and deletion in flash memories

In a memory that is programmable page by page and each page having multiple sectors that are once-programmable, even if successive writes are sequential, the data recorded to an update block may be fragmented and non-sequential. Instead of recording update data to an update block, the data is being recorded in at least two interleaving streams. When a full page of data is available, it is recorded to the update block. Otherwise, it is temporarily recorded to the scratch pad block until a full page of data becomes available to be transferred to the update block. Preferably, a pipeline operation allows the recording to the update block to be set up as soon as the host write command indicates a full page could be written. If the actual write data is incomplete due to interruptions, the setup will be canceled and recording is made to the scratch pad block instead.

Non-volatile memory and method with multi-stream updating

In a nonvolatile memory with block management system that supports update blocks with non-sequential logical units, an index of the logical units in a non-sequential update block is buffered in RAM and stored periodically into the nonvolatile memory. In one embodiment, the index is stored in a block dedicated for storing indices. In another embodiment, the index is stored in the update block itself. In yet another embodiment, the index is stored in the header of each logical unit. In another aspect, the logical units written after the last index update but before the next have their indexing information stored in the header of each logical unit. In this way, after a power outage, the location of recently written logical units can be determined without having to perform a scanning during initialization. In yet another aspect, a block is managed as partially sequential and partially non-sequential, directed to more than one logical subgroup.

Non-volatile memory and method with non-sequential update block management

A non-volatile memory is constituted from a set of memory planes, each having its own set of read/write circuits so that the memory planes can operate in parallel. The memory is further organized into erasable blocks, each for storing a logical group of logical units of data. In updating a logical unit, all versions of a logical unit are maintained in the same plane as the original. Preferably, all versions of a logical unit are aligned within a plane so that they are all serviced by the same set of sensing circuits. In a subsequent garbage collection operation, the latest version of the logical unit need not be retrieved from a different plane or a different set of sensing circuits, otherwise resulting in reduced performance. In one embodiment, any gaps left after alignment are padded by copying latest versions of logical units in sequential order thereto.

Non-volatile memory and method with memory planes alignment

Direct data file storage in flash memories

A re-programmable non-volatile memory system, such as a flash EEPROM system, having its memory cells grouped into blocks of cells that are simultaneously erasable is operated in a manner to level out the wear of the individual blocks through repetitive erasing and re-programming. This may be accomplished without use of counts of the number of times the individual blocks experience erase and re-programming but such counts can optionally aid in carrying out the wear leveling process. Individual active physical blocks are chosen to be exchanged with those of an erased block pool in a predefined order.

Cyclic flash memory wear leveling

The on-chip copy process is extended so that the data may be copied between two blocks that may be on different chips, different planes on the same chip, or the same plane of the same chip. More specifically, the methods described here provide a single data copying mechanism that allows data to be copied between any two locations in a memory system. An exemplary embodiment uses an EDO-type timing. According to another aspect, selected portions of the relocated data, such as chosen words in a transferred page, can be updated in the controller on the fly. In addition to transferring a data set directly from a read buffer of a source array to a write buffer of a destination array, the data set can concurrently be copied, if desired, into the controller where an error detection and correction operation can be performed on it.

Off-chip data relocation

Techniques for managing data in a non-volatile memory system (e.g., Flash Memory) are disclosed. A controller can use information relating to a host's filing system, which is stored by the host on non-volatile memory, to determine if one or more clusters (or sectors with clusters) are currently allocated. The controller can use the information relating to the host's filing system to ensure that one or more clusters (or one or more sectors within a cluster) are not copied from one location to another location in the memory during a garbage collection cycle. As a result, some unnecessary operations (e.g., copying data) which are conventionally performed can be avoided and system performance can be enhanced.

Method and apparatus for maintaining data on non-volatile memory systems

Update data to a non-volatile memory may be recorded in at least two interleaving streams such as either into an update block or a scratch pad block depending on a predetermined condition. The scratch pad block is used to buffered update data that are ultimately destined for the update block. In a preferred embodiment, an index of the data stored in the scratch pad block as well that stored in the update block is saved in an unused portion of the scratch pad block every time the scratch pad block is written to.

Non-volatile memory and method with improved indexing for scratch pad and update blocks

Update data to a non-volatile memory may be recorded in at least two interleaving streams such as either into an update block or a scratch pad block depending on a predetermined condition. The scratch pad block is used to buffered update data that are ultimately destined for the update block. Synchronization information about the order recording of updates among the streams is saved with at least one of the streams. This will allow the most recently written version of data that may exist on multiple memory blocks to be identified. In one embodiment, the synchronization information is saved in a first block and is a write pointer that points to the next recording location in a second block. In another embodiment, the synchronization information is a time stamp.

Non-volatile memory and method with multi-stream update tracking

A non-volatile memory system is organized in physical groups of physical memory locations. Each physical group (metablock) is erasable as a unit and can be used to store a logical group of data. A memory management system allows for update of a logical group of data by allocating a metablock dedicated to recording the update data of the logical group. The update metablock records update data in the order received and has no restriction on whether the recording is in the correct logical order as originally stored (sequential) or not (chaotic). Eventually the update metablock is closed to further recording. One of several processes will take place, but will ultimately end up with a fully filled metablock in the correct order which replaces the original metablock. In the chaotic case, directory data is maintained in the non-volatile memory in a manner that is conducive to frequent updates. The system supports multiple logical groups being updated concurrently.

Non-volatile memory and method with block management system

In one embodiment of the present invention, there is disclosed, a method of handling data which is being written to and stored in flash memory, wherein input data, comprising information data and overhead data, undergoes a reversible transformation before being written to flash memory whereupon each bit stored in flash memory, as flash data, is a function of both information data and header data.

Growing community of inventors

Midlothian, United Kingdom

Peter John Smith