Western Digital Technologies, Inc.

Kai-Lung Cheng

Yun-Tzuo Lai

Jerry Lo

Subhash Balakrishna Pillai

Eugene Lisitsyn

Haining Liu

Parvaneh Alavi

A device that provides error recovery handling includes a processor that is configured to receive an error recovery request including error type information and a page address, where the error type information is mapped to a first error recovery technique. The processor may be configured to determine whether an error count associated with the flash memory circuit satisfies a first criterion and an error map associated with the flash memory circuit satisfies a second criterion, where the error count indicates a number of read errors that have occurred and the error map indicates blocks in which the read errors have occurred. The processor may be configured to utilize a second technique to attempt to recover data when the first and second criterions are satisfied, otherwise utilize the first technique to attempt to recover data, where the second technique is associated with recovering data stored in an offline flash memory circuit.

Error recovery handling

The subject technology provides for managing a data storage system. A host write command to write host data associated with a logical address to a non-volatile memory is received. A first physical address in the non-volatile memory mapped to the logical address in an address mapping table is determined. An indicator that the first physical address is bad checked. If the first physical address is indicated as bad, a valid count associated with a first set of physical addresses at a current value is maintained. The first set of physical addresses comprises the first physical address. If the first physical address is not indicated as bad, the first physical address is marked as invalid. The valid count associated with the first set of physical addresses is decremented.

Managing data for a data storage system

Host data segments are received and stored in a cached data unit corresponding to a previously stored data unit currently stored in non-volatile memory. Metadata is created that identifies unmodified previously stored segments of host data in the previously stored data unit that correspond to the received host data segments, the metadata including an update flag indicating that the previously stored data unit requires updating. In response to detecting the unexpected interruption of power, the cached data unit and the metadata is written to an area of the non-volatile memory array that is different than where the previously stored data unit is currently stored. Upon resuming operation following the unexpected interruption of power, the cached data unit is identified based on the update flag, as having been saved in response to the power shutdown without the previously stored data unit being updated in the non-volatile memory array, and then reloaded into the memory cache.

Preserving data upon a power shutdown

Managing system data for a data storage system

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Irvine, CA, United States of America

Kai-Lung Cheng