T30 NAND Flash wear health report

I am trying to gauge wear on the T30 NAND Flash (Micron part: MTFC4GACAJCN-1M WT). The part we have uses MLC. According to the ECSD datasheet, Device lifetime type B (register 269) refers to MLC and Device lifetime type A (register 268) refers to SLC.

After running a program to write for a couple of days, I see device lifetime type A go up to 0x7, but type B stays at 0x1. However, it’s confusing since this part allegedly has MLC only. I tested further and now the value of type A is at 0xb, which is the highest possible and means that it has exceeded estimated device lifetime. However it happily still writes to flash for a while after still testing…

Do you have any insight to this? Maybe that register is used on accident or documented wrong?

The PDF with the ECSD register info I am referring is here: http://www.farnell.com/datasheets/3151200.pdf

I am using the memdump toradex tool to dump the ECSD register information


Since this part is an MLC the register 268 can be ignored, I assume.