HOST MANUAL REFRESH OPTIMIZATION FOR A DATA STORAGE DEVICE
A data storage device includes a data retention risk system that identifies memory blocks having a data retention risk and are candidates for a host manual refresh operation. The data retention risk system identifies memory blocks having a data retention risk by finding memory blocks with valid data. The data retention risk system determines an age of the data stored by the memory block using timestamp information associated with the data and/or the memory block. If the age of the data is over an age threshold, the memory block is initially classified as having a data retention risk. The memory blocks that have been classified as having a data retention risk are further categorized based on a severity of the data retention risk.
1 . A method, comprising:
identifying one or more memory blocks of a data storage device having valid data;
determining a first timestamp associated with the data storage device;
determining a second timestamp associated with at least one memory block of the one or more memory blocks, the second timestamp being stored as metadata in the at least one memory block;
comparing the first timestamp to the second timestamp to determine a difference between the first timestamp and the second timestamp;
comparing the difference between the first timestamp and the second timestamp to a timestamp difference threshold;
determining based, at least in part, on the comparing the difference between the first timestamp and the second timestamp to a timestamp difference threshold, whether the at least one memory block has a data retention risk;
in response to determining the at least one memory block has a data retention risk:
determining a bit error rate (BER) associated with the at least one memory block;
categorizing a severity of the data retention risk of the at least one memory block based, at least in part, on comparing the BER to one or more BER thresholds; and
providing the categorization of the severity of the at least one memory block to a host device to enable the host device to selectively initiate a host manual refresh operation on the at least one memory block.
2 . (canceled)
3 . The method of claim 1 , further comprising determining a bit error rate (BER) level on at least one wordline of the at least one memory block.
4 . The method of claim 1 , wherein categorizing the severity of the data retention risk of the at least one memory block comprises categorizing the at least one memory block as having at least one of a high data retention risk, a medium data retention risk and a low data retention risk.
5 . The method of claim 1 , further comprising grouping the at least one memory block with other memory blocks having a similar severity.
6 . The method of claim 1 , wherein identifying the one or more memory blocks of the data storage device having valid data comprises generating a bitmap that indicates which memory blocks of the one or more memory blocks have valid data.
7 . The method of claim 1 , further comprising:
determining a total number of memory blocks in the data storage device having valid data;
determining a number of memory blocks of the total number of memory blocks that can undergo the host manual refresh operation in a given time period; and
providing the determined number of memory blocks to the host device to enable the host device to determine a number of host manual refresh command operations to issue to the data storage device.
8 . A data storage device, comprising:
a controller; and
a data retention risk system associated with the controller and operable to:
identify memory blocks of the data storage device having valid data;
determine a bit error rate (BER) associated with each of the memory blocks in response to determining the memory blocks have a data retention risk;
categorize a severity of the data retention risk of the memory blocks based, at least in part, on comparing the BER to one or more BER thresholds; and
provide the categorization of the severity of the data retention risk of the memory blocks to a host device to enable the host device to selectively initiate a host manual refresh operation on the memory blocks.
9 . The data storage device of claim 8 , wherein the data retention risk system is further operable to reset the timestamp associated with the data storage device in response to a time synchronization event.
10 . The data storage device of claim 9 , wherein the time synchronization event is at least one of a power cycle event, a power down event and a power up event.
11 . (canceled)
12 . The data storage device of claim 8 , wherein categorizing the severity of the data retention risk of the memory blocks having the data retention risk comprises categorizing the memory blocks as having at least one of a high data retention risk, a medium data retention risk and a low data retention risk.
13 . The data storage device of claim 8 , wherein the data retention risk system is further operable to group the memory blocks based, at least in part, on the severity of the data retention risk.
14 . The data storage device of claim 8 , wherein the data retention risk system is further operable to generate a bitmap that indicates which memory blocks have valid data.
15 . The data storage device of claim 8 , wherein the data retention risk system is further operable to:
determine a total number of memory blocks having valid data;
determine a number of memory blocks of the total number of memory blocks that can be manually refreshed in a given time period; and
provide the determined number of memory blocks to the host device to enable the host device to determine a number of host manual refresh command operations to issue to the data storage device.
16 . A data storage device, comprising:
means for identifying memory blocks of the data storage device having valid data;
means for determining a bit error rate (BER) associated with each of the memory blocks in response to determining the memory blocks have a data retention risk;
means for categorizing a severity of the data retention risk of the memory blocks based. at least in part, on comparing the BER to one or more BER thresholds; and
means for providing the categorization of the severity of the memory blocks to a host device to enable the host device to selectively initiate a host manual refresh operation on the memory blocks.
17 . The data storage device of claim 16 , further comprising means for resetting the timestamp associated with the data storage device in response to a time synchronization event.
18 . (canceled)
19 . The data storage device of claim 16 , wherein the means for categorizing the severity of the data retention risk of the memory blocks having the data retention risk categorizes the memory blocks as having at least one of a high data retention risk, a medium data retention risk and a low data retention risk.
20 . The data storage device of claim 16 , further comprising means for grouping the memory blocks based, at least in part, on the severity of the data retention risk.
21 . The method of claim 1 , further comprising ordering the at least one memory block within a risk category based, at least in part, on the BER associated with the at least one memory block.
22 . The data storage device of claim 8 , wherein the data retention risk system is further operable to provide, to the host device, a number of memory blocks in at least one risk category to enable the host device to determine a number of host manual refresh commands to issue.
23 . The data storage device of claim 16 , further comprising means for providing, to the host device, a number of memory blocks in at least one risk category to enable the host device to determine a number of host manual refresh commands to issue.