# US 8,572,443 B2 · System, method, and computer program product for determining a retention behavior for at least one block of a memory device having finite endurance and/or retention > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,572,443 B2 - Document ID: US8572443B2 - Status: Granted - Kind: B2 - Application number: 12/420,589 - Filed: 2009-04-08 - Published: 2010-10-14 - Granted: 2013-10-29 - Earliest claimed: 2009-04-08 - Assignees: International Business Machines Corporation - Applicants: Steven Robert Hetzler; William John Kabelac - Inventors: Steven Robert Hetzler; William John Kabelac - Web page: https://patentgrep.com/patent/US8572443B2 ## CPC - G06F 12/0246: {in block erasable memory, e.g. flash memory} - G11C 16/349: {Arrangements for evaluating degradation, retention or wearout, e.g. by counting erase cycles} - G11C 29/50016: {of retention} - G11C 29/52: Protection of memory contents; Detection of errors in memory contents - G06F 2212/7211: Wear leveling - G11C 16/04: using variable threshold transistors, e.g. FAMOS - G11C 2029/0409: {Online test} - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - G11C: STATIC STORES (semiconductor memory devices H10B) ## Abstract A method according to one embodiment includes writing monitor data to at least one block of a memory device having finite endurance and/or retention; reading the monitor data after a period of time; determining a retention behavior of the at least one block based on the reading; and outputting a result of the determining. A memory device according to one embodiment includes a plurality of memory blocks having finite endurance and/or retention, at least one of the blocks having monitor data written therein; and circuitry for addressing the blocks. A system according to one embodiment includes a memory device having finite endurance and/or retention, the memory device comprising: a plurality of memory blocks, at least one of the blocks having monitor data written therein, wherein the at least one block has been written to a plurality of times prior to writing the monitor data; and circuitry for addressing the blocks. ## Claims ### Claim 1 A memory device, comprising: a plurality of memory blocks having finite endurance and/or retention, at least one of the blocks having monitor data written therein; and circuitry for addressing the blocks, wherein the monitor data is written to multiple groups of blocks, and wherein a number of write cycles performed for each group is different. ### Claim 2 (depends on 1) A method, comprising: writing monitor data to at least one block of a memory device as recited in claim 1; reading the monitor data after a period of time; determining a retention behavior of the at least one block based on the reading; and outputting a result of the determining, wherein the monitor data is written to multiple groups of blocks, and wherein a number of write cycles performed for each group is different. ### Claim 3 (depends on 2) The system of claim 2, wherein the monitor data is: (i) data of known content stored in dedicated memory cells of known write cycle count, (ii) not subject to wear leveling, and (iii) write protected for preventing the monitor data from being overwritten with user data. ### Claim 4 (depends on 2) The method of claim 2, further comprising selecting multiple blocks of the memory device for storing the monitor data, at least two of the blocks not being physically adjacent each other. ### Claim 5 (depends on 2) The method of claim 2, wherein the at least one block has been written to a plurality of times prior to writing the monitor data, wherein at least one of the blocks having monitor data written therein is has a write cycle count near an expected rise of a cumulative distribution function (CDF) for wearout. ### Claim 6 (depends on 2) The method of claim 2, with the proviso that the monitor data is not subject to wear leveling, wherein user data is subject to wear leveling. ### Claim 7 (depends on 2) The method of claim 2, wherein at least a portion of the at least one block having the monitor data is write protected. ### Claim 8 (depends on 2) The method of claim 2, wherein the monitor data is known to a host system, wherein the determining the retention behavior includes comparing the read monitor data to a version thereof stored on the host system. ### Claim 9 (depends on 2) The method of claim 2, wherein determining the retention behavior includes measuring a retention and endurance of the at least one block. ### Claim 10 (depends on 2) The method of claim 2, wherein the monitor data comprises less than about 1% of a memory capacity of the memory device. ### Claim 11 (depends on 2) The method of claim 2, further comprising performing the reading and determining at periodic intervals. ### Claim 12 (depends on 2) The method of claim 2, further comprising determining an operational limit of the memory device or portion thereof based on the result of the determining. ### Claim 13 (depends on 12) The method of claim 12, further comprising no longer allowing writes to the memory device or portion thereof when the operation limit is met. ### Claim 14 (depends on 1) The memory device of claim 1, wherein at least two of the blocks have the monitor data written therein and are not physically adjacent each other. ### Claim 15 (depends on 1) The memory device of claim 1, wherein at least a portion of the at least one block having the monitor data is write protected. ### Claim 16 (depends on 15) The memory device of claim 15, wherein wherein at least two of the blocks have the monitor data written therein and are not physically adjacent each other, with the proviso that the monitor data is not subject to wear leveling, wherein writing of user data to the memory blocks is subject to wear leveling. ### Claim 17 (depends on 1) The memory device of claim 1, wherein the monitor data comprises less than about 1% of a memory capacity of the memory device. ### Claim 18 (depends on 1) The memory device of claim 1, with the proviso that the monitor data is not subject to wear leveling. ### Claim 19 (depends on 1) The memory device of claim 1, wherein the at least one block has been written to a plurality of times prior to writing the monitor data, wherein at least one of the blocks having monitor data written therein is has a write cycle count near an expected rise of a cumulative distribution function (CDF) for wearout. ### Claim 20 A computer program product, comprising: a non-transitory computer usable medium having computer usable program code embodied therewith, the computer usable program code comprising: computer usable program code configured to write monitor data to at least one block of a memory device, the memory device comprising: a plurality of memory blocks having finite endurance and/or retention, at least one of the blocks having monitor data written therein, and circuitry for addressing the blocks, wherein the monitor data is written to multiple groups of blocks, and wherein a number of write cycles performed for each group is different; computer usable program code configured to read the monitor data after a period of time; computer usable program code configured to determine a retention behavior of the at least one block based on the reading; computer usable program code configured to output a result of the determining; computer usable program code configured to provide wear leveling when writing user data to the memory blocks, with the proviso that the monitor data is not subject to wear leveling. ### Claim 21 A system, comprising: a memory device having finite endurance and/or retention, the memory device comprising: a plurality of memory blocks, at least one of the blocks having monitor data written therein, wherein the at least one block has been written to a plurality of times prior to writing the monitor data; and circuitry for addressing the blocks, with the proviso that the monitor data is not subject to wear leveling, a module for subjecting writing of user data to wear leveling. ### Claim 22 (depends on 21) The system of claim 21, wherein the monitor data is: (i) data of known content stored in dedicated memory cells of known write cycle count, (ii) not subject to wear leveling, and (iii) write protected for preventing the monitor data from being overwritten with user data. ### Claim 23 (depends on 21) The system of claim 21, further comprising a non-transitory computer usable medium, the computer usable medium having computer usable program code embodied therewith, which when executed by a processor causes the processor to: write the monitor data to the at least one block of a memory device having finite endurance and/or retention; read the monitor data after a period of time; determine a retention behavior of the at least one block based on the reading; and output a result of the determining. ### Claim 24 (depends on 21) The system of claim 21, further comprising a storage controller and a plurality of the memory devices. ### Claim 25 (depends on 21) The system of claim 21, wherein at least two of the blocks have the memory data written therein and are not physically adjacent each other.