hesela.deveMMC Device Life Time Estimation
eMMC Device Life Time Estimation reports estimated average wear of memory types A and B relative to their estimated maximum lifetimes.
The A/B fields occupy EXT_CSD bytes 268/269. Codes 0x01 through 0x0A identify successive ten-percentage-point bands of used life; 0x0B means the estimated maximum has been exceeded. Zero is undefined and 0x0C-0xFF are reserved. [1]
The pinned mmc-utils decoder gates this generic reporting at eMMC 5.0. Preserve both raw values and the device-specific meaning of A/B rather than inventing a universal NAND-cell-type mapping. [2]
More detailed, device-specific wear reporting can supplement the coarse endurance estimates. A band is not an exact wear percentage, remaining calendar lifetime or calibrated failure probability. An unchanged code between observations does not demonstrate zero additional wear within that band. [3]
Relations
Citations
- JEDEC JESD84-B51 (February 2015), sections 7.4.22-7.4.24, pages 182-183; TI-hosted copy
- mmc-utils c6692d5: health-command revision gate and lifetime/PRE_EOL decoders
- Kingston: eMMC Life-Cycle Estimating, Validating & Monitoring (January 2023)
Further reading
Sources & caveats
- Source-reviewed field semantics, not measurements from a device or a JEDEC conformance test.
- The limits on calendar-time, failure-probability and unchanged-code interpretation are editorial inferences from the field semantics.