3 ms·

I used to work in flash manufacturing. We would joke, "I hope nobody ever uses this for swap!" The numbers I saw for endurance (basically write-erase cycles b

I used to work in flash manufacturing. We would joke, "I hope nobody ever uses this for swap!" The numbers I saw for endurance (basically write-erase cycles before failure) were not encouraging at all. As far as I can tell the only reason MLC flash works at all is that the controller does some magic to present a whole bunch of pretty flaky cells as a single reliable unit.

Dylan16807 9y ago
> As far as I can tell the only reason MLC flash works at all is that the controller does some magic to present a whole bunch of pretty flaky cells as a single reliable unit. I would refuse to even use SLC flash without that magic. But once you have all that ECC and balancing, durability almost stops being a problem outside of heavy database loads.
warrenm 9y ago
>I used to work in flash manufacturing How long ago? r/w cycles haven't really been an issue on SSDs in a long time
- sevensor 9y ago
  2010. I've been following the industry since I left, and I promise you neither the physics of FN flash nor the manufacturing process has fundamentally changed since then. Nor have the true endurance numbers substantially improved. If anything the situation is worse now with smaller device dimensions. The only thing standing between your collection of cat gifs and oblivion is the flash controller making intelligent guesses about what it just read.
  - warrenm 9y ago
    Sorry, but you must not be "following the industry" very well. SSDs have lifespans measured in years of constant use. If you think it isn't the case, you need to go back and learn more about those devices you claim to know so much about.
    - sevensor 9y ago
      I'm afraid we're misunderstanding each other here. You're talking about the fully-integrated SSD. Not my area of expertise. I'm talking about the endurance of the flash cell transistors. Nobody's claiming significantly higher endurance for the transistors themselves -- what's improved is the stuff on top of them. SSD controllers have gotten better at not trashing any given cell with repeated program / erase cycles. If you measure endurance of modern SSDs versus seven years ago, sure, you'll see better endurance, but that's becasue there's better logic on top, not because the cell transistors are any better than they were.
      - detaro 9y ago
        But as a user putting the SSD into my machine I don't care about the low-level cells, I care about what's in the datasheet of the device I bought?
        tinus_hn 9y ago
        The magic of the SSD controller can introduce rather surprising failure modes that you should probably care about.
        sevensor 9y ago
        Fair point. As with eating sausages, so with using flash memory. Maybe easier to make a rational decision about it if you haven't seen it made.

Dylan16807 9y ago

> As far as I can tell the only reason MLC flash works at all is that the controller does some magic to present a whole bunch of pretty flaky cells as a single reliable unit. I would refuse to even use SLC flash without that magic. But once you have all that ECC and balancing, durability almost stops being a problem outside of heavy database loads.

warrenm 9y ago

>I used to work in flash manufacturing How long ago? r/w cycles haven't really been an issue on SSDs in a long time

sevensor 9y ago
2010. I've been following the industry since I left, and I promise you neither the physics of FN flash nor the manufacturing process has fundamentally changed since then. Nor have the true endurance numbers substantially improved. If anything the situation is worse now with smaller device dimensions. The only thing standing between your collection of cat gifs and oblivion is the flash controller making intelligent guesses about what it just read.
- warrenm 9y ago
  Sorry, but you must not be "following the industry" very well. SSDs have lifespans measured in years of constant use. If you think it isn't the case, you need to go back and learn more about those devices you claim to know so much about.
  - sevensor 9y ago
    I'm afraid we're misunderstanding each other here. You're talking about the fully-integrated SSD. Not my area of expertise. I'm talking about the endurance of the flash cell transistors. Nobody's claiming significantly higher endurance for the transistors themselves -- what's improved is the stuff on top of them. SSD controllers have gotten better at not trashing any given cell with repeated program / erase cycles. If you measure endurance of modern SSDs versus seven years ago, sure, you'll see better endurance, but that's becasue there's better logic on top, not because the cell transistors are any better than they were.
    - detaro 9y ago
      But as a user putting the SSD into my machine I don't care about the low-level cells, I care about what's in the datasheet of the device I bought?
      - tinus_hn 9y ago
        The magic of the SSD controller can introduce rather surprising failure modes that you should probably care about.
      - sevensor 9y ago
        Fair point. As with eating sausages, so with using flash memory. Maybe easier to make a rational decision about it if you haven't seen it made.