Radian Memory Systems, Inc.

Mike Jadon

Andrey V Kuzmin

Robert Lercari

Craig Robertson

Alan Chen

Richard M Mathews

This disclosure provides for host-controller cooperation in managing NAND flash memory. The controller maintains information for each erase unit which tracks memory usage. This information assists the host in making decisions about specific operations, for example, initiating garbage collection, space reclamation, wear leveling or other operations. For example, metadata can be provided to the host identifying whether each page of an erase unit has been released, and the host can specifically then command each of consolidation and erase using direct addressing. By redefining host-controller responsibilities in this manner, much of the overhead association with FTL functions can be substantially removed from the memory controller, with the host directly specifying physical addresses. This reduces performance unpredictability and overhead, thereby facilitating integration of solid state drives (SSDs) with other forms of storage. The disclosed techniques are especially useful for direct-attached and/or network-attached storage.

Nonvolatile memory controller

This disclosure provides techniques hierarchical address virtualization within a memory controller and configurable block device allocation. By performing address translation only at select hierarchical levels, a memory controller can be designed to have predictable I/O latency, with brief or otherwise negligible logical-to-physical address translation time. In one embodiment, address transition may be implemented entirely with logical gates and look-up tables of a memory controller integrated circuit, without requiring processor cycles. The disclosed virtualization scheme also provides for flexibility in customizing the configuration of virtual storage devices, to present nearly any desired configuration to a host or client.

Hierarchical storage device with host controlled subdivisions

This disclosure provides a memory controller for asymmetric non-volatile memory, such as flash memory, and related host and memory system architectures. The memory controller is configured to automatically generate and transmit redundancy information to a destination, e.g., a host or another memory drive, to provide for cross-drive redundancy. This redundancy information can be error correction (EC) information, which is linearly combined with similar information from other drives to create 'superparity.' If EC information is lost for one drive, it can be rebuilt by retrieving the superparity, retrieving or newly generating EC information for uncompromised drives, and linearly combining these values. In one embodiment, multiple error correction schemes are used, including a first intra-drive scheme to permit recovery of up to x structure-based failures, and the just-described redundancy scheme, to provide enhanced security for greater than x structure-based failures.

Erasure coding techniques for flash memory

This disclosure provides techniques for managing writes of data useful for storage systems that do not permit overwrite of a logical address. One implementation provides a nonvolatile memory storage drive, such as a flash memory drive, that provides support for zoned drive and/or Open Channel-compliant architectures. Circuitry on the storage drive tracks storage location release metadata for addressable memory space, optionally providing to a host system information upon which maintenance decisions or related scheduling can be based. The storage drive can also provide buffering support for accommodating receipt of out-of-order writes and unentanglement and performance of out of order writes, with buffering resources being configurable according to any one of a number of parameters. The disclosed storage drive facilitates reduced error rates and lower request traffic in a manner consistent with newer memory standards that mandate that writes to logical addresses be sequential.

Techniques for managing writes in nonvolatile memory

Processing functions are offloaded to a memory controller for nonvolatile memory by a host in connection with write data. The nonvolatile memory executes these functions, producing processed data that must be written into memory; for example, the offloaded functions can include erasure coding, with the nonvolatile memory controller generating redundancy information that must be written into memory. The memory controller holds this information in internal RAM and then later writes this information into nonvolatile memory according to dynamically determined write time and/or destinations selected by the host, so as to not collide with host data access requests. In one embodiment, the memory is NAND flash memory and the memory controller is a cooperative memory controller that permits the host to schedule concurrent operations in respective, configurable virtual block devices which have been configured by the host out of a pool of structural flash memory structures managed by the memory controller.

Growing community of inventors

Manhattan Beach, CA, United States of America

Mike Jadon