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https://www.xda-developers.com/your-unpowered-ssd-is-slowly-losing-your-data/
SSDs have all but replaced hard drives when it comes to primary storage. They're orders of magnitude faster, more convenient, and consume less power than mechanical hard drives. That said, if you're also using SSDs for cold storage, expecting the drives lying in your drawer to work perfectly after years, you might want to rethink your strategy. Your reliable SSD could suffer from corrupted or lost data if left unpowered for extended periods. This is why many users don't consider SSDs a reliable long-term storage medium, and prefer using hard drives, magnetic tape, or M-Disc instead.
Unlike hard drives that magnetize spinning discs to store data, SSDs modify the electrical charge in NAND flash cells to represent 0 and 1. NAND flash retains data in underlying transistors even when power is removed, similar to other forms of non-volatile memory. However, the duration for which your SSD can retain data without power is the key here. Even the cheapest SSDs, say those with QLC NAND, can safely store data for about a year of being completely unpowered. More expensive TLC NAND can retain data for up to 3 years, while MLC and SLC NAND are good for 5 years and 10 years of unpowered storage, respectively.
The problem is that most consumer SSDs use only TLC or QLC NAND, so users who leave their SSDs unpowered for over a year are risking the integrity of their data. The reliability of QLC NAND has improved over the years, so you should probably consider 2–3 years of unpowered usage as the guardrails. Without power, the voltage stored in the NAND cells can be lost, either resulting in missing data or completely useless drives.
This data retention deficiency of consumer SSDs makes them an unreliable medium for long-term data storage, especially for creative professionals and researchers. HDDs can suffer from bit rot, too, due to wear and tear, but they're still more resistant to power loss. If you haven't checked your archives in a while, I'd recommend doing so at the earliest.
(Score: 5, Interesting) by JoeMerchant on Sunday November 30, @02:00PM (1 child)
SSDs are charge storage devices, the longevity of the data depends on high impedance (resistance) barriers between cells.
When they were brand new (10-ish years ago) SSDs were rated to hold data for 10 years "when new."
As they are used (mostly write cycles) those resistive barriers break down - a very pro- business feature ensuring replacement sales. After they wear down, data retention times dwindle to a year of power off, then to a month or less.
Of course this wear doesn't happen evenly, so much has been done around "wear leveling algorithms," which, of course, are not all equally successful. Some models of SSD exhibit worn out behavior much faster than others. In addition to wear leveling, there are also error correcting schemes which prevent data loss, up to a point.
One warning sign of an SSD "on the edge" is very slow read and write performance, particularly slow boot times.
One way to mask these issues is to keep your SSDs continuously powered, of course this means that when you finally do power it off, your data is gone the next time you power it up.
Some newer SSDs are longer wearing, most newer SSDs are just bigger and cheaper, but that's a good thing too because if you have a 4TB SSD that you use for the same data activity as a 100GB SSD, the 4TB drive will wear out 40x slower.
🌻🌻🌻 [google.com]
(Score: 2, Interesting) by Anonymous Coward on Monday December 01, @01:18AM
The temperature when the data was written and the temperature when it was stored also matters according to stuff 10 years ago:
https://archive.is/1lW1R [archive.is]
Note: the article linked to was about stuff past endurance ratings.