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Comment by vee-kay | Hacker News Reader

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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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.

Bottom of the barrel flash drives..

Many of us have old cheap flash drives, which may have some backups (family photos, videos, career files, etc.) we may not want to lose - so they may qualify for such periodic basic maintenance (just plugging them into the PC once in 6 months or so).

I think most home users don't know this can be a potential problem for flash drive storage.

> of a bottom of the barrel SSD wildly exceeding expectations.

I heard enough of stories of a bottom of the barrel SSDs wildly exceeding expectations by actually crashing with a partial or a full data loss waaay below their expected write endurance and while still powered on. Sure, these are the real bottom of the barrel, like Netac or KingSpec - but I won't expect any non-server grade SSD to retain data at all for any meaningful time.

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.

CD-R media is of limited shelf life as well though

But the materials on the CD eventually break down, sometimes as soon as within 5 years. So you can look into MDisc, which purports 100 years…but only in theory since the tests are just approximations of what would actually happen.

Totally could be a defect in the lamination we don’t find out for years yet

Having had drives which sat for many years and spun right back up without corruption makes me think 1% is too generous maybe 0.05% per year at most

The claim you're responding to is that hard drives lose "magnetic charge" at a rate of 1% per year, not that bits get corrupted at a rate of 1% per year. The error correction in hard drives is far simpler and weaker than what's used in SSDs, but it does exist. So we should expect that there's a significant margin for data degradation before any observable data corruption begins. (This is true for SSDs, too; the first symptom of data degradation is reduced read performance as slower, more complex error correction methods kick in, then much later the host starts to actually get read errors or bad data.)

The magnetic strength of particles on the disk can decay at 1% per year, but the drive won't have issues reading them until they fall below a threshold where they can no longer be read. It could take decades.

Magnetic HDDs also tend to have inbuilt SMART features to monitor disk performance and health, so they can inform when they are beginning to give problems. So the advanced user can recover the data before the HDD fully fails.

In my experience, flash drives tend to get problems suddenly leading to data corruption, and it may not be immediately apparent to the user till it is too late. I haven't such problems in recent years though, so maybe flash drives have become smarter too.

The important distinction here is that CD-ROMs can store data indefinitely, but CD-Rs and CD-RWs can not.

BD-R and M-Disc CD and DVDs have archival storage life.

As an industry insider, I have never heard the one percent. I'm not saying that it's not possible, but I don't recall ever hearing of us testing for it. So what is the source of the 1%?

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