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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 en

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.
      - wtallis 1y ago
        > 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? Probably not, assuming they're using the same underlying media and same strength of ECC and that the amount of host data written was appropriately adjusted to account for the different capacities and overprovisioning ratios to ensure the actual P/E cycles seen by the NAND were the same. As you write more data, the consumer drive would be out of warranty first, while the enterprise drive would still be under warranty but not spec'd to retain data for as long as the worn-out consumer drive. So for either drive, the manufacturer isn't guaranteeing 1 year retention past the rated endurance of the consumer drive.
      - 1y ago

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.
    - wtallis 1y ago
      > 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? Probably not, assuming they're using the same underlying media and same strength of ECC and that the amount of host data written was appropriately adjusted to account for the different capacities and overprovisioning ratios to ensure the actual P/E cycles seen by the NAND were the same. As you write more data, the consumer drive would be out of warranty first, while the enterprise drive would still be under warranty but not spec'd to retain data for as long as the worn-out consumer drive. So for either drive, the manufacturer isn't guaranteeing 1 year retention past the rated endurance of the consumer drive.
    - 1y ago