I'm curious about the endurance of QLC. P/E cycles for SLC are around 100,000, MLC around 10,000 and TLC around 1,000. Each generation results in an order of magnitude worse endurance. For QLC we’ve yet to see whether the P/E cycle will be in the 100 range or whether manufacturers have managed to make the technology more reliable somehow. Low 3-digit write endurance could make these drives relatively worthless, except for long term storage of permanent files that require no writes, such as movies, video footage, music, and photos. Anything that require writes, like an OS, application, or game, would quickly wear out the drive (maybe a year?)

Reading has no effect on endurance, so once you fill up that movie or music drive, it should last forever, as long as you don't ever change anything (be sure you get all the tags/cover art perfect before writing). But the price would have to be close to HDDs (2-3¢ /GB) to be feasible, not 20¢/GB as these are. This looks more promising for extremely cheap SATA drives. All this hinges on the actual write endurance of QLC flash cells, of course.

Also, the long term archive persistence (retention) is unknown - will these QLC cells still hold correct digital values after a few months, much less 10 or 20 years down the road? Or will the voltages tend to drift, like the problems already encountered with TLC (reads become progressively slower the longer data is stored). Samsung dealt with this by using an algorithm that periodically re-writes all the files, so that they never have a chance to deteriorate - not ideal, since write endurance is limited on TLC, so this work-around isn't even feasible on QLC.

I suppose we'll have to wait for the accelerated endurance tests that hammer the drive with write/erase cycles. If Intel has conducted these kind of tests, they're not talking.

Posted on Aug 1st 2018, 19:40 Reply