[gymbeaux]

I remember reading something somewhere about a guy doing tests on "3D" NAND and other TLC/MLC NAND SSDs and finding that data was lost well before the "10 years or so" that we have come to assume unpowered SSDs can retain data for. I can't locate that article at the moment but it isn't unreasonable to expect faster degradation on denser NAND.

[wtallis]

The 3D in 3D NAND doesn't belong in scare quotes; the physical arrangement of the memory cells really is three-dimensional and it isn't just a marketing term. The transition from planar NAND to 3D NAND turned back the clock by several years in terms of shrinking memory cell volume and charge differences between adjacent data states.

The SSDs that caught the most flak for poor retention characteristics were using the last generation of planar NAND, in a three bit per cell configuration, which in hindsight was a bit of an overreach. But even then, the worst symptoms that could be reliably reproduced were poor performance reading back stale data, a result of the drives having to use higher levels of ECC to recover the data. (More recent SSDs have vastly more powerful controllers capable of running LDPC calculations much faster.) That's not quite the same as losing data.