3 ms·

To ground these endurance figures a little more concretely, consumer drives will advertise 600TBW:TB, or 600 cycles! Starting at 10x that is a very solid starti

To ground these endurance figures a little more concretely, consumer drives will advertise 600TBW:TB, or 600 cycles! Starting at 10x that is a very solid starting place! On the other hand, an enterprise drive like Kioxia CM7 will offer either 1 or 3 drive writes per day (for regular and write-intensive drive models, respectively), across the 5 year warranty. That's ~1800 cycles or just shy of 5500 cycles.

userbinator 1y ago
Enterprise drives have always been rated for lower retention and hence higher cycles than consumer drives, since those are inversely correlated.
- daymanstep 1y ago
  Do you have a source for that claim? Everything I've read suggests that data retention is mostly about the write temperature vs storage temperature, and that enterprise drives have about equivalent retention to consumer drives. By retention I'm assuming you're referring to the amount of time it takes for data loss to occur on SSDs in cold unpowered storage.
  - userbinator 1y ago
    From the horse's mouth: https://americas.kioxia.com/content/dam/kioxia/en-us/business/memory/mlc-nand/asset/KIOXIA_NAND_Flash_Data_Retention_Technical_Brief.pdf https://americas.kioxia.com/content/dam/kioxia/en-us/busines... (See graph on page 2.) https://www.macronix.com/Lists/ApplicationNote/Attachments/1920/AN0339V1-Endurance%20and%20Retention%20of%20NAND%20Flash.pdf https://www.macronix.com/Lists/ApplicationNote/Attachments/1... (See graph on page 3.) Then look up the retention specs for enterprise drives and compare to consumer ones, and the conclusion is obvious.
    - daymanstep 1y ago
      Correct me if I'm mistaken but it looks to me like your graphs are talking about the number of P/E cycles accumulated, rather than the number of P/E cycles that a drive is rated for? What this seems to suggest is that as a drive gets more "worn out", its data retention gets worse. But I don't see how that can be taken to imply that enterprise drives have worse data retention than consumer drives. Nothing that I've seen suggests this.
      - zozbot234 1y ago
        > What this seems to suggest is that as a drive gets more "worn out", its data retention gets worse. This is what informal tests (i.e. via scrubbing/resilvering the drive after leaving it powered off for a long time) have found. Retention/data remanence is remarkably good for a drive that has been written over just once, and quite bad (i.e. you start seeing bit errors) for one that's almost worn out. This is actually very good news for the EEPROM-like use case where rewrites are quite rare. (Note that "almost worn out" in this case can mean going far beyond the formal total-data-written rating of the drive. We're talking the range where the hardware itself is about to croak.)
      - userbinator 1y ago
        But I don't see how that can be taken to imply that enterprise drives have worse data retention than consumer drives Look up the specs. Commonly quoted as 3 months for enterprise ratings but the whole picture is in these tables: https://www.legitreviews.com/wp-content/uploads/2015/05/ssd-temps-endurance.jpg https://www.legitreviews.com/wp-content/uploads/2015/05/ssd-... Page 22 of this "says the quiet part out loud": https://www.snia.org/sites/default/files/AnilVasudeva_Are_SSDs_Ready_Enterprise_Storage_Systemsv4.pdf https://www.snia.org/sites/default/files/AnilVasudeva_Are_SS... ("Lower Data Retention allows for higher endurance")
        daymanstep 1y ago
        I'm not sure I fully understand what that page is saying. It is my understanding that JEDEC standard tests the data retention of the "worst case" scenario where a drive is fully worn out, i.e the drive has reached its maximum rated P/E cycles. If I'm understanding correctly, that page you linked is saying that enterprise drives have firmware that essentially allows more P/E cycles, which then means that at the end of those cycles, the drive will be more "worn out" and thus will have a worse data retention. But in a real world usage scenario where we subject a consumer SSD and an enterprise SSD to the same number of P/E cycles, would they have different data retention? I thought the JEDEC data was only for end-of-life scenarios.
justincormack 1y ago
Generally they just chop off some space to allow for more to be used when it wears out, which is why enterprise is 3.84TB not 4TB. If you partition the drive smaller and never use the rest you can achieve similar endurance.

userbinator 1y ago

Enterprise drives have always been rated for lower retention and hence higher cycles than consumer drives, since those are inversely correlated.

daymanstep 1y ago
Do you have a source for that claim? Everything I've read suggests that data retention is mostly about the write temperature vs storage temperature, and that enterprise drives have about equivalent retention to consumer drives. By retention I'm assuming you're referring to the amount of time it takes for data loss to occur on SSDs in cold unpowered storage.
- userbinator 1y ago
  From the horse's mouth: https://americas.kioxia.com/content/dam/kioxia/en-us/business/memory/mlc-nand/asset/KIOXIA_NAND_Flash_Data_Retention_Technical_Brief.pdf https://americas.kioxia.com/content/dam/kioxia/en-us/busines... (See graph on page 2.) https://www.macronix.com/Lists/ApplicationNote/Attachments/1920/AN0339V1-Endurance%20and%20Retention%20of%20NAND%20Flash.pdf https://www.macronix.com/Lists/ApplicationNote/Attachments/1... (See graph on page 3.) Then look up the retention specs for enterprise drives and compare to consumer ones, and the conclusion is obvious.
  - daymanstep 1y ago
    Correct me if I'm mistaken but it looks to me like your graphs are talking about the number of P/E cycles accumulated, rather than the number of P/E cycles that a drive is rated for? What this seems to suggest is that as a drive gets more "worn out", its data retention gets worse. But I don't see how that can be taken to imply that enterprise drives have worse data retention than consumer drives. Nothing that I've seen suggests this.
    - zozbot234 1y ago
      > What this seems to suggest is that as a drive gets more "worn out", its data retention gets worse. This is what informal tests (i.e. via scrubbing/resilvering the drive after leaving it powered off for a long time) have found. Retention/data remanence is remarkably good for a drive that has been written over just once, and quite bad (i.e. you start seeing bit errors) for one that's almost worn out. This is actually very good news for the EEPROM-like use case where rewrites are quite rare. (Note that "almost worn out" in this case can mean going far beyond the formal total-data-written rating of the drive. We're talking the range where the hardware itself is about to croak.)
    - userbinator 1y ago
      But I don't see how that can be taken to imply that enterprise drives have worse data retention than consumer drives Look up the specs. Commonly quoted as 3 months for enterprise ratings but the whole picture is in these tables: https://www.legitreviews.com/wp-content/uploads/2015/05/ssd-temps-endurance.jpg https://www.legitreviews.com/wp-content/uploads/2015/05/ssd-... Page 22 of this "says the quiet part out loud": https://www.snia.org/sites/default/files/AnilVasudeva_Are_SSDs_Ready_Enterprise_Storage_Systemsv4.pdf https://www.snia.org/sites/default/files/AnilVasudeva_Are_SS... ("Lower Data Retention allows for higher endurance")
      - daymanstep 1y ago
        I'm not sure I fully understand what that page is saying. It is my understanding that JEDEC standard tests the data retention of the "worst case" scenario where a drive is fully worn out, i.e the drive has reached its maximum rated P/E cycles. If I'm understanding correctly, that page you linked is saying that enterprise drives have firmware that essentially allows more P/E cycles, which then means that at the end of those cycles, the drive will be more "worn out" and thus will have a worse data retention. But in a real world usage scenario where we subject a consumer SSD and an enterprise SSD to the same number of P/E cycles, would they have different data retention? I thought the JEDEC data was only for end-of-life scenarios.

justincormack 1y ago

Generally they just chop off some space to allow for more to be used when it wears out, which is why enterprise is 3.84TB not 4TB. If you partition the drive smaller and never use the rest you can achieve similar endurance.