A method for operating a memory (28) that includes a plurality of analog memory cells (32) includes storing data in the memory by writing first storage values to the cells. Second storage values are read from the cells, and a Cumulative Distribution Function (CDF) of the second storage values is estimated. The estimated CDF is processed so as to compute one or more thresholds. A memory access operation is performed on the cells using the one or more thresholds.

Adaptive Estimation of Memory Cell Read Thresholds

A method for operating a memory (28) includes storing data, which is encoded with an Error Correction Code (ECC), in analog memory cells (32) of the memory by writing respective analog input values selected from a set of nominal values to the analog memory cells. The stored data is read by performing multiple read operations that compare analog output values of the analog memory cells to different, respective read thresholds so as to produce multiple comparison results for each of the analog memory cells. At least two of the read thresholds are positioned between a pair of the nominal values that are adjacent to one another in the set of the nominal values. Soft metrics are computed responsively to the multiple comparison results. The ECC is decoded using the soft metrics, so as to extract the data stored in the analog memory cells.

Reading memory cells using multiple thresholds

In order to provide a more efficient persistent storage device, one or more long-term storage media are included along with a non-volatile memory. In one embodiment, one portion of the non-volatile memory is used as a write buffer and a read cache for writes and reads to the long-term storage media. Interfaces are provided for controlling the use of the non-volatile memory as a write buffer and a read cache. Additionally, a portion of the non-volatile memory is used to provide a direct mapping for specified sectors of the long-term storage media. Descriptive data regarding the persistent storage device is stored in another portion of the non-volatile memory.

Non-volatile memory cache performance improvement

A method for operating a memory (28) includes storing data in a group of analog memory cells (32) of the memory as respective first voltage levels. After storing the data, second voltage levels are read from the respective analog memory cells. The second voltage levels are affected by cross-coupling interference causing the second voltage levels to differ from the respective first voltage levels. Cross-coupling coefficients, which quantify the cross-coupling interference among the analog memory cells, are estimated by processing the second voltage levels. The data stored in the group of analog memory cells is reconstructed from the read second voltage levels using the estimated cross-coupling coefficients.

Distortion estimation and cancellation in memory devices

A method for storing data in a memory (28) that includes analog memory cells (32) includes identifying one or more defective memory cells in a group of the analog memory cells. An Error Correction Code (ECC) is selected responsively to a characteristic of the identified defective memory cells. The data is encoded using the selected ECC and the encoded data is stored in the group of the analog memory cells. In an alternative method, an identification of one or more defective memory cells among the analog memory cells is generated. Analog values are read from the analog memory cells in which the encoded data were stored, including at least one of the defective memory cells. The analog values are processed using an ECC decoding process responsively to the identification of the at least one of the defective memory cells, so as to reconstruct the data.

Automatic defect management in memory devices

In accordance with one or more aspects, compressed storage management in a system includes determining which of multiple data units stored in an uncompressed portion of the storage resource are to be compressed and stored in a compressed portion of the storage resource The management can further include returning one or more regions of the compressed portion for use in the uncompressed portion in response to storage resource pressure in the system, as well as compacting regions in the compressed portion to fill empty gaps in the compressed portion

Compressed storage management

The invention is directed towards a system and method that utilizes external memory devices to cache sectors from a rotating storage device (e.g., a hard drive) to improve system performance. When an external memory device (EMD) is plugged into the computing device or onto a network in which the computing device is connected, the system recognizes the EMD and populates the EMD with disk sectors. The system routes I/O read requests directed to the disk sector to the EMD cache instead of the actual disk sector. The use of EMDs increases performance and productivity on the computing device systems for a fraction of the cost of adding memory to the computing device.

Using external memory devices to improve system performance

Embodiments of the invention provide techniques for ensuring that the contents of a non-volatile memory device may be relied upon as accurately reflecting data stored on disk storage across a power transition such as a reboot. For example, some embodiments of the invention provide techniques for determining whether the cache contents and/or or disk contents are modified during a power transition, causing cache contents to no longer accurately reflect data stored in disk storage. Further, some embodiments provide techniques for managing cache metadata during normal ("steady state") operations and across power transitions, ensuring that cache metadata may be efficiently accessed and reliably saved and restored across power transitions.

Managing cache data and metadata

Increased efficiency in booting a computer uses a process of logging physical-level disk access during a boot cycle for use in creating a boot plan for a subsequent boot. Processing the log from one or more previous boots removes unnecessary reads such as those associated with temporary files and then orders the remaining read accesses based on times of prior read accesses and and by physical location on the disk. Upon boot, data likely to be requested first orders the remaining read accesses based on times of prior read accesses and By taking advantage of disk head and platter characteristics, data is read in sweeps through the disk, reducing overall latency. Requests that are not in cache may be held if the data is already scheduled for retrieval.

Accelerated system boot

A method and apparatus for managing the caching of data on an auxiliary memory of a computer. Pages of data may be cached on an auxiliary memory, such as a flash memory, at a virtual level using an identifier that does not involve a physical address of the pages on a memory. Pages may be cached on auxiliary memory that may be removable from the computer, e.g., by unplugging the memory from the computer. Page data may be encrypted and/or compressed on the auxiliary memory. An authentication indicator may be used to verify the accuracy of cached data in the case of an interrupted connection to the auxiliary memory, e.g., as a result of computer power down, hibernation, removal of the memory from the computer, etc.

Alexander Kirshenbaum

Papers

Compressed storage management

Using external memory devices to improve system performance

Managing cache data and metadata

Accelerated system boot

Management of external memory functioning as virtual cache