3 ms·

And NAND has an electrical charge that will dissipate, eventually leading to data loss. This time period is on the order of 90 days (I think I’ve seen some data

And NAND has an electrical charge that will dissipate, eventually leading to data loss. This time period is on the order of 90 days (I think I’ve seen some data sheets saying 30 days) up to one year. https://www.jedec.org/sites/default/files/Alvin_Cox%20%5BCompatibility%20Mode%5D_0.pdf https://www.jedec.org/sites/default/files/Alvin_Cox%20%5BCom... https://www.ibm.com/support/pages/potential-ssd-data-loss-after-extended-shutdown https://www.ibm.com/support/pages/potential-ssd-data-loss-af... The OCP NVMe Cloud SSD Specification states that drives must not have data loss when powered off for up to 30 days and that when powered on data must me rewritten to refresh data that may have started to lose charge while powered off. Search for retention in: https://www.opencompute.org/documents/nvme-cloud-ssd-specification-v1-0-3-pdf https://www.opencompute.org/documents/nvme-cloud-ssd-specifi...

xyzzy123 4y ago
Your overall point is valid (there are lifetime constraints that mean you shouldn't rely on unpowered SSDs for long term archiving) but IMHO your post is overly pessimistic. The spec is 1 year minimum for client and 3mo for server, but most drives exceed that. This thread includes a response from a Micron rep: https://community.spiceworks.com/topic/944779-enterprise-ssds-powered-off-potentially-lose-data-in-a-week https://community.spiceworks.com/topic/944779-enterprise-ssd... "The very most important thing to realize when looking at these charts is that the data retention number stated are for SSDs which have reached the end of their useful life. They're worn out. If you have an enterprise-class SSD which is rated for 5 petabytes of writes over its lifetime (just to pick a typical number) , then you will not see this 3 month data retention number until you've actually written 5 petabytes to the drive. When NAND Flash is brand new out of the box, the data retention is actually several years (although we typically don't rate data retention when new). Honestly, Flash-based storage probably isn't optimal for unpowered archiving. That three-month, EOL spec reflects this. In enterprise computing, when the NAND lifetime is used up, the intent should be to move any important data to a new device (or wipe the old device for security reasons). In client computing (notebooks and desktops), we rarely see the typical user getting to the point where NAND wearout is a concern, so we rarely see data retention as an issue, either. So, you needn't be concerned about data retention until your SSD gets really, really old."
- mgerdts 4y ago
  That makes sense. The numbers from standards and spec sheets do look quite pessimistic compared to the retention I’ve experienced with cheap USB drives and old SD cards that are rarely powered.

xyzzy123 4y ago

Your overall point is valid (there are lifetime constraints that mean you shouldn't rely on unpowered SSDs for long term archiving) but IMHO your post is overly pessimistic. The spec is 1 year minimum for client and 3mo for server, but most drives exceed that. This thread includes a response from a Micron rep: https://community.spiceworks.com/topic/944779-enterprise-ssds-powered-off-potentially-lose-data-in-a-week https://community.spiceworks.com/topic/944779-enterprise-ssd... "The very most important thing to realize when looking at these charts is that the data retention number stated are for SSDs which have reached the end of their useful life. They're worn out. If you have an enterprise-class SSD which is rated for 5 petabytes of writes over its lifetime (just to pick a typical number) , then you will not see this 3 month data retention number until you've actually written 5 petabytes to the drive. When NAND Flash is brand new out of the box, the data retention is actually several years (although we typically don't rate data retention when new). Honestly, Flash-based storage probably isn't optimal for unpowered archiving. That three-month, EOL spec reflects this. In enterprise computing, when the NAND lifetime is used up, the intent should be to move any important data to a new device (or wipe the old device for security reasons). In client computing (notebooks and desktops), we rarely see the typical user getting to the point where NAND wearout is a concern, so we rarely see data retention as an issue, either. So, you needn't be concerned about data retention until your SSD gets really, really old."

mgerdts 4y ago
That makes sense. The numbers from standards and spec sheets do look quite pessimistic compared to the retention I’ve experienced with cheap USB drives and old SD cards that are rarely powered.