A simplistic physics interpretation would also balk at the extremely low glide elevations of your typical spinning rust.
That would be a misunderstanding of the science involved in "spinning rust". Magnetic fields are, when properly attenuated, extremely reliable. That was a comparison that did not lend itself to a good argument.
A rechargable battery would be a better comparison and more similar in function. A battery works by applying a voltage to change the chemistry of the compounds within a battery for the purpose of holding a charge. When that charge is used, the chemistry reverts back to a lower charge state until recharged again. However, the chemical compounds within that battery can only withstand a certain number of charge discharge cycles before rendering them unusable.
NAND cells are very similar. When voltage is applied, the charge state for the cell changes. Change the voltage in a different way and the cell resets to it's default state. That is an SLC cycle. 2 Voltage cycles are needed for change an SLC block to default(NAND is always written to in blocks) and 1 more to set the state of each NAND cell within that block.
An MLC write cycle works as follows: A voltage state is applied to reset the Block being written too. Then another is applied the set the new data being written to the block. The voltage is then altered and applied again to make a third state. This requires a slight increase of voltage when compared to the first voltage application cycle. A total of three voltage cycles need to be applied to the NAND to alter MLC cells.
A TLC write state works the same way, but has a fourth voltage application cycle.
A QLC write cycle adds a fifth cycle.
With each write cycle, an additional voltage is applied to the cell and at a slightly increased voltage each time. With each of these write cycles, the chemistry of the NAND cell degrades by a small but not insignificant amount.
With SLC, there is 2 voltage cycles applied for every change made. With MLC, 3. TLC, 4. QLC, 5. PLC, 6.
It should be very clear to anyone who understands this process that with each voltage cycle, at an increased voltage with each, that a NAND cell will quickly and easily degrade. TLC is on the bleeding edge of what can be considered an acceptable level of NAND cell wear. QLC, pushes beyond that acceptable level and effectively relegates it to the areas of incidental storage. QLC is is fine if you only plan to use it lightly a for a year or two. Beyond that, it becomes increasingly unfavorable and unreliable. And that is ONLY if the NAND cells do not experience a cascade voltage failure, which is a known problem within the NAND industry.
QLC is untrustworthy after a certain period of time, no matter what the manufacturers claim.
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