Secure erasure of data from a non-volatile memory
First Claim
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1. A method comprising:
- identifying an extended data set comprising multiple copies of data having a common logical address stored in different physical addresses within the memory, the multiple copies comprising a most current copy of the data and at least one stale copy of the data;
determining a total accumulated size of the extended data set indicative of an accumulated total number of data bits in the multiple copies of the data stored in each of the different physical addresses within the memory;
comparing the overall size of the extended data set to a predetermined threshold; and
sanitizing at least a portion of the extended data set from the memory in relation to the overall size of the data set so that other previously stored data in the memory are retained in the memory, wherein a first type of sanitizing operation is performed responsive to the overall size of the extended data set exceeding the predetermined threshold and a different, second type of sanitizing operation is performed responsive to the overall size not exceeding the predetermined threshold.
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Abstract
Method and apparatus for securely erasing data from a non-volatile memory, such as but not limited to a flash memory array. In accordance with various embodiments, an extended data set to be sanitized from the memory is identified. The extended data set includes multiple copies of data having a common logical address and different physical addresses within the memory. The extended data set is sanitized in relation to a characterization of the data set. The data sanitizing operation results in the extended data set being purged from the memory and other previously stored data in the memory being retained.
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Citations
23 Claims
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1. A method comprising:
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identifying an extended data set comprising multiple copies of data having a common logical address stored in different physical addresses within the memory, the multiple copies comprising a most current copy of the data and at least one stale copy of the data; determining a total accumulated size of the extended data set indicative of an accumulated total number of data bits in the multiple copies of the data stored in each of the different physical addresses within the memory; comparing the overall size of the extended data set to a predetermined threshold; and sanitizing at least a portion of the extended data set from the memory in relation to the overall size of the data set so that other previously stored data in the memory are retained in the memory, wherein a first type of sanitizing operation is performed responsive to the overall size of the extended data set exceeding the predetermined threshold and a different, second type of sanitizing operation is performed responsive to the overall size not exceeding the predetermined threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus comprising:
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a non-volatile memory which stores an extended data set comprising multiple copies of data having a common logical address and different physical addresses within the memory, the multiple copies comprising a most current version of the data and at least one stale version of the data; and a controller adapted to determine an overall size of the extended data set, to compare the overall size to a predetermined threshold, and to sanitize the extended data set from the memory responsive to said determined overall size exceeding the predetermined threshold so that the entire extended data set is non-destructively and permanently purged from the memory and other data in the memory are retained, wherein the overall size of the extended data set is indicative of an accumulated total number of data bits in the multiple copies of the data stored in each of the different physical addresses within the memory; in which the controller performs a first type of sanitizing operation upon the extended data set responsive to a first overall size of the extended data set exceeding the predetermined threshold and performs a different, second type of sanitizing operation responsive to a different, second overall size of the extended data set less than the predetermined threshold. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A storage device comprising a non-volatile memory, a monitor circuit, and a controller adapted to, responsive to a trigger signal generated by the monitor circuit, sanitize an extended data set from the non-volatile memory responsive to an overall size of the data set, the data set comprising multiple copies of host data sharing a common logical address and having different physical addresses within the memory, said multiple copies comprising a most current version of the data and a plurality of older, stale versions of the data, said sanitizing operable to purge the extended data set from the memory so that the most current version of the data and the plurality of older, stale versions of the data are permanently removed from the memory while retaining other host data in the memory, wherein the overall size of the extended data set is indicative of an accumulated total number of data bits in the multiple copies of the data stored in each of the different physical addresses within the memory;
in which the controller applies a first data sanitizing operation to the memory responsive to the overall size exceeding a predetermined threshold, the controller applying a different, second data sanitizing operation to the memory responsive to the overall size not exceeding the predetermined threshold. - View Dependent Claims (19, 20, 21, 22, 23)
Specification