Defect management policies for NAND flash memory
First Claim
1. A method of managing defects in a nonvolatile storage system, the nonvolatile storage system including one or more nonvolatile memory (NVM) devices, the method comprising:
- monitoring, by an NVM defect management policy engine, a plurality of trigger events for detecting one or more possible defects in an NVM device among the one or more NVM devices, the respective trigger events having corresponding types, the NVM device including a plurality of physical memory pages, each physical memory page including a plurality of NVM storage locations;
having monitored a first trigger event among the plurality of trigger events for detecting a possible defect among the one or more possible defects in the NVM device, determining, by the NVM defect management policy engine, a trigger event type among the corresponding types of the respective trigger events that corresponds to the first trigger event, the first trigger event corresponding to a first NVM storage location among the plurality of NVM storage locations included in a respective one of the plurality of physical memory pages of the NVM device;
determining, by the NVM defect management policy engine, a likelihood of monitoring a second trigger event among the plurality of trigger events that (1) has a same trigger event type as the first trigger event, and (2) corresponds to a second NVM storage location among the plurality of NVM storage locations included in the respective one of the plurality of physical memory pages of the NVM device; and
having determined the likelihood of monitoring the second trigger event, proactively retiring, by the NVM defect management policy engine, the respective one of the plurality of physical memory pages of the NVM device based on the trigger event type of the first trigger event.
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Abstract
Systems and methods of managing defects in nonvolatile storage systems that can be used to avoid an inadvertent loss of data, while maintaining as much useful memory in the nonvolatile storage systems as possible. The disclosed systems and methods can monitor a plurality of trigger events for detecting possible defects in one or more nonvolatile memory (NVM) devices included in the nonvolatile storage systems, and apply one or more defect management policies to the respective NVM devices based on the types of trigger events that resulted in detection of the possible defects. Such defect management policies can be used proactively to retire memory in the nonvolatile storage systems with increased granularity, focusing the retirement of memory on regions of nonvolatile memory that are likely to contain a defect.
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Citations
20 Claims
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1. A method of managing defects in a nonvolatile storage system, the nonvolatile storage system including one or more nonvolatile memory (NVM) devices, the method comprising:
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monitoring, by an NVM defect management policy engine, a plurality of trigger events for detecting one or more possible defects in an NVM device among the one or more NVM devices, the respective trigger events having corresponding types, the NVM device including a plurality of physical memory pages, each physical memory page including a plurality of NVM storage locations; having monitored a first trigger event among the plurality of trigger events for detecting a possible defect among the one or more possible defects in the NVM device, determining, by the NVM defect management policy engine, a trigger event type among the corresponding types of the respective trigger events that corresponds to the first trigger event, the first trigger event corresponding to a first NVM storage location among the plurality of NVM storage locations included in a respective one of the plurality of physical memory pages of the NVM device; determining, by the NVM defect management policy engine, a likelihood of monitoring a second trigger event among the plurality of trigger events that (1) has a same trigger event type as the first trigger event, and (2) corresponds to a second NVM storage location among the plurality of NVM storage locations included in the respective one of the plurality of physical memory pages of the NVM device; and having determined the likelihood of monitoring the second trigger event, proactively retiring, by the NVM defect management policy engine, the respective one of the plurality of physical memory pages of the NVM device based on the trigger event type of the first trigger event. - View Dependent Claims (2)
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3. A method of managing defects in a nonvolatile storage system, the nonvolatile storage system including one or more nonvolatile memory (NVM) devices, the method comprising:
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monitoring, by and NVM defect management policy engine, a plurality of trigger events for detecting one or more possible defects in an NVM device among the one or more NVM devices, the respective trigger events having associated types; having monitored a trigger event among the plurality of trigger events for detecting a possible defect among the one or more possible defects in the NVM device, determining, by the NVM defect management policy engine, a type among the associated types of the respective trigger events that corresponds to the monitored trigger event; and applying, by the NVM defect management policy engine, at least one defect management policy to the NVM device based on the type of the monitored trigger event, wherein the plurality of trigger events include a soft bit read trigger event and an exclusive-or (XOR) data recovery trigger event, wherein the type of the monitored trigger event include one of a soft bit read trigger event type corresponding to the soft bit read trigger event and an XOR data recovery trigger event type corresponding to the XOR data recovery trigger event, and wherein the applying of the at least one defect management policy to the NVM device includes retiring an NVM storage location of a codeword for which a host processor issued a data read request. - View Dependent Claims (4)
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5. A method of managing defects in a nonvolatile storage system, the nonvolatile storage system including one or more nonvolatile memory (NVM) devices, the method comprising:
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monitoring, by and NVM defect management policy engine, a plurality of trigger events for detecting one or more possible defects in an NVM device among the one or more NVM devices, the respective trigger events having associated types; having monitored a trigger event among the plurality of trigger events for detecting a possible defect among the one or more possible defects in the NVM device, determining, by the NVM defect management policy engine, a type among the associated types of the respective trigger events that corresponds to the monitored trigger event; and applying, by the NVM defect management policy engine, at least one defect management policy to the NVM device based on the type of the monitored trigger event, wherein the plurality of trigger events include a predetermined number of hard bit read trigger events, wherein the type of the monitored trigger event includes a hard bit read trigger event type corresponding to the predetermined number of hard bit read trigger events, and wherein the applying of the at least one defect management policy to the NVM device includes retiring an NVM storage location of a codeword for which a host processor issued one or more data read requests. - View Dependent Claims (6, 7, 8, 9)
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10. A nonvolatile storage system, comprising:
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an nonvolatile memory (NVM) controller; one or more NVM devices communicably coupled to the NVM controller; and an NVM defect management policy engine communicably coupled to the NVM controller, wherein the NVM defect management policy engine is operative; to monitor a plurality of trigger events for detecting one or more possible defects in an NVM device among the one or more NVM devices, the respective trigger events having corresponding types, the NVM device including a plurality of physical memory pages, each physical memory page including a plurality of NVM storage locations; having monitored a first trigger event among the plurality of trigger events for detecting a possible defect among the one or more possible defects in the NVM device, to determine a trigger event type among the corresponding types of the respective trigger events that corresponds to the first trigger event, the first trigger event corresponding to a first NVM storage location among the plurality of NVM storage locations included in a respective one of the plurality of physical memory pages of the NVM device; to determine a likelihood of monitoring a second trigger event among the plurality of trigger events that (1) has a same trigger event type as the first trigger event, and (2) corresponds to a second NVM storage location among the plurality of NVM storage locations included in the respective one of the plurality of physical memory pages of the NVM device; and having determined the likelihood of monitoring the second trigger event, to proactively retire the respective one of the plurality of physical memory pages of the NVM device based one the trigger event type of the first trigger event. - View Dependent Claims (11)
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12. A nonvolatile storage system, comprising:
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a nonvolatile memory (NVM) controller; one or more NVM devices communicably coupled to the NVM controller; and an NVM defect management policy engine communicably coupled to the NVM controller, wherein the NVM defect management policy engine is operative; to monitor a plurality of trigger events for detecting one or more possible defects in an NVM device among the one or more NVM devices, the respective trigger events having associated types; having monitored a trigger event among the plurality of trigger events for detecting a possible defect among the one or more possible defects in the NVM device, to determine a type among the associated types of the respective trigger events that corresponding to the monitored trigger event; and to apply at least one defect management policy to the NVM device based on the type of the monitored trigger event, wherein the plurality of trigger events include a soft bit read trigger event and an exclusive-or (XOR) data recovery trigger event, wherein the type of the monitored trigger event includes one of a soft bit read trigger event type corresponding to the soft bit read trigger event and an XOR data recovery trigger event type corresponding to the XOR data recovery trigger event, and wherein the NVM defect management policy engine is further operative, having monitored the soft bit read trigger event or the XOR data recovery trigger event, to retire an NVM storage location of a codeword for which a host processor issued a data read request. - View Dependent Claims (13)
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14. A nonvolatile storage system, comprising:
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a nonvolatile memory (NVM) controller; one or more NVM devices communicably coupled to the NVM controller; and an NVM defect management policy engine communicably coupled to the NVM controller, wherein the NVM defect management policy engine is operative; to monitor a plurality of trigger events for detecting one or more possible defects in an NVM device among the one or more NVM devices, the respective trigger events having associated types; having monitored a trigger event among the plurality of trigger events for detecting a possible defect among the one or more possible defects in the NVM device, to determine a type among the associated types of the respective trigger events that corresponding to the monitored trigger event; and to apply at least one defect management policy to the NVM device based on the type of the monitored trigger event, wherein the plurality of trigger events include a predetermined number of hard bit read trigger events, wherein the type of the monitored trigger event includes a hard bit read trigger event type corresponding to the predetermined number of hard bit read trigger events, and wherein the NVM defect management policy engine is further operative, having monitored the predetermined number of hard bit read trigger events, to retire an NVM storage location of a codeword for which a host processor issued one or more data read requests. - View Dependent Claims (15, 16)
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17. A nonvolatile storage system including one or more nonvolatile memory (NVM) devices, the system comprising:
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means for monitoring a plurality of trigger events for detecting one or more possible defects in an NVM device among the one or more NVM devices, the respective trigger events having corresponding types, the NVM device including a plurality of physical memory pages, each physical memory page including a plurality of NVM storage locations; having monitored a first trigger event among the plurality of trigger events for detecting a possible defect among the one or more possible defects in the NVM device, means for determining a trigger event type among the corresponding types of the respective trigger events that corresponds to the first trigger event, the first trigger event corresponding to a first NVM storage location among the plurality of NVM storage locations included in a respective one of the plurality of physical memory pages of the NVM device; means for determining a likelihood of monitoring a second trigger event among the plurality of trigger events that (1) has a same trigger event type as the first trigger event, and (2) corresponds to a second NVM storage location among the plurality of NVM storage locations included in the respective one of the plurality of physical memory pages of the NVM device; and having determined the likelihood of monitoring the second trigger event, means for proactively retiring the respective one of the plurality of physical memory pages of the NVM device based on the trigger event type of the first trigger event. - View Dependent Claims (18)
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19. A non-transitory computer-readable storage medium including executable instructions for accessing data storable within a non-volatile memory (NVM) device in a computer system, the computer system including at least one processor, the non-transitory computer-readable storage medium comprising executable instructions:
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to monitor a plurality of trigger events for detecting one or more possible defects in the NVM device, the respective trigger events having associated types; having monitored a trigger event among the plurality of trigger events for detecting a possible defect among the one or more possible defects in the NVM device, to determine a type among the associated types of the respective trigger events that corresponds to the monitored trigger event; and to apply at least one defect management policy to the NVM device based on the type of the monitored trigger event, wherein the plurality of trigger events include a soft bit read trigger event and an exclusive-or (XOR) data recovery trigger event, wherein the type of the monitored trigger event includes one of a soft bit read trigger event type corresponding to the soft bit read trigger event and an XOR data recovery trigger event type corresponding to the XOR data recovery trigger event, and wherein the non-transitory computer-readable storage medium further comprises executable instructions, having monitored the soft bit read trigger event or the XOR data recovery trigger event, to retire an NVM storage location of a codeword for which a host processor issued a data read request. - View Dependent Claims (20)
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Specification