3 ms·

I want to point out this is worst case retention after the maximum guaranteed writes are done to the SSD. For a typical SSD that means 70TB to 150TB. An SSD whi

I want to point out this is worst case retention after the maximum guaranteed writes are done to the SSD. For a typical SSD that means 70TB to 150TB. An SSD which is not close to that level of writing will retain for much longer. My Crucial m4 from 2 years ago, which I regularly abuse - full disk encryption (more random IO), no TRIM (eventually filling the SSD), and I am at 98% life (i.e. I have used only 2%). The retention at this point is much more than a year. Yes, I expect that if I write something and leave my SSD on the shelf it will be readable in 5 years or more.

lisper 11y ago
> The retention at this point is much more than a year. How do you know?
- sfilipov 11y ago
  You are right I don't have emperic data. Maybe I'm wrong. The reason I believe that retention is higher until you exhaust the cell cycles is explained in the article. For instance, the reason why the active temperature during which writes were done is because lower temperature during such time will somehow strain cells more. But that effect will be noticable if you are close to exhaustion of the cell cycles. Let's say that 3000 write cycles at temperature best for retention are equal to 2000 write cycles at suboptimal temperatures (that's on the pessimistic side I believe). Well, that's order(s) of magnitude less than the amount of writes a normal user does. The cycles I've used should be ~60 out of 3000. If I've used 2 orders of magnitude less cycles than the product is designed to survive, I expect to have retention which is at least a multiple of the guaranteed one after all cycles (1 year). In other words, what makes SSDs to eventually fail reads is that the cells can't hold charge. They can't hold charge because the insulation has been damaged ("by design"). At 2% of the designed cycles, the cells are almost brand new, retention of electrons within cells is great.

lisper 11y ago

> The retention at this point is much more than a year. How do you know?

sfilipov 11y ago
You are right I don't have emperic data. Maybe I'm wrong. The reason I believe that retention is higher until you exhaust the cell cycles is explained in the article. For instance, the reason why the active temperature during which writes were done is because lower temperature during such time will somehow strain cells more. But that effect will be noticable if you are close to exhaustion of the cell cycles. Let's say that 3000 write cycles at temperature best for retention are equal to 2000 write cycles at suboptimal temperatures (that's on the pessimistic side I believe). Well, that's order(s) of magnitude less than the amount of writes a normal user does. The cycles I've used should be ~60 out of 3000. If I've used 2 orders of magnitude less cycles than the product is designed to survive, I expect to have retention which is at least a multiple of the guaranteed one after all cycles (1 year). In other words, what makes SSDs to eventually fail reads is that the cells can't hold charge. They can't hold charge because the insulation has been damaged ("by design"). At 2% of the designed cycles, the cells are almost brand new, retention of electrons within cells is great.