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vee-kayyesterday at 6:08 PM2 repliesview on HN

Technically, that magnetic spinning HDD can work even after decades if maintained safely (no dust, no extreme heat) and without stress, even if it is not switched on for years.

In fact, if a magnetic HDD crashes, you may still recover some or all of the data by doing something hardcore, such as letting it sit for some hours in the freezer of your refrigerator, or immersing it in a bowl of rice overnight.

However, SSDs (and other flash storage devices) need to be switched on once in few months, otherwise there's a chance that some data stored in them may be permanently lost, as some cells may loose their power.

"As a reminder, an SSD's endurance rating is calculated based on how long it can store data if left unplugged after a certain amount of data has been written": https://www.tomshardware.com/pc-components/storage/unpowered...


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wtallisyesterday at 7:25 PM

I feel like maybe you didn't understand the meaning of that last bit you quoted from Tom's Hardware. To be clear: the standard for consumer SSDs is 1 year of unpowered data retention after the drive's full write endurance rating has been exhausted.

The experiment Tom's is reporting on found twelve instances of data corruption on a low-end drive that had been subjected to over two thousand full drive writes, four times its rated write endurance, then left on a shelf for two years. This is a demonstration of a bottom of the barrel SSD wildly exceeding expectations.

It's really important in conversations like this to accurately convey not just the existence of the failure mode, but also the realistic chances of running into this problem, and the extent of the problem when it does manifest. If a deliberate torture test can only produce a few kilobytes of data corruption after twice the duration and four times the abuse the drive is supposed to be able to handle, this problem should be described as extremely minor.

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daymanstepyesterday at 6:26 PM

HDDs also lose magnetic charge over time, about 1% per year. So you need to periodically spin up and rewrite the data every few years.

CD drives however, can store data indefinitely without needing refreshing.

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