[cwizou]

In general, there are two separate components to the SLC cache strategy (which as you said, is writing only one bit instead of 3 for TLC, because it's much faster to do so). First you have some overprovisionned NAND, the size of which depends with models. I believe it is 6 GB on this one.

Then you have what they call "intelligent turbowrite", which is a dynamically allocated/reallocated SLC cache (about 108 GB).

For both, the concept is broadly the same, your writes go into the overprovisionned "SLC cache" first, then into the dynamic one.

When the drive is idle, it will consolidate the writes of both caches as 3 bit writes, freeing the NAND for "SLC cache" use again. This can take a few minutes of idle time.

As you fill up your disk things get more complicated, you need to keep some free space to be able to consolidate your writes, the exact way this controller works in that case is not known to me, but this is an issue with every SSD that's not full SLC. Modern controllers usually are doing much better than the old ones.