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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: 2, Insightful) by pTamok on Monday December 01, @02:22PM (3 children)
That sounds very, very similar to a couple of my war stories.
> you should verify on a different LTO drive to the one that wrote the tape
This is a/the key point. When verifying your backup, check also that it is readable in a different reader. Always.
(Score: 4, Interesting) by Unixnut on Monday December 01, @03:16PM (2 children)
No doubt, every war story I've heard follows a similar pattern. Usually involving prior bad decisions, lack of funding/interest from those in charge (who are not technically savvy) and an unfortunate disaster. I've been through a fair few of them. The "basements flooding" disaster were quite common, because back then the basement was the one place nobody wanted to work or be in but is a space which the company paid for, so logically it was the best place to put servers as they did not care about the smell or lack of natural light and thereby save money on office rental space.
The irony of the situation in my war story, is that after all that cost and rigmarole, the beancounters actually rejected our request to buy a second LTO drive, pointing out we now have a new one that has just been verified as "calibrated", so everything is now fine.
Back then I could not understand the short sightedness, but nowadays I have learned that there is a difference between capital and operational expenditure when it comes to tax write-offs and accounting, so perhaps it was the financially better off decision they made for the company.
Head misalignment is a common issue with devices where the recording medium is not always matched to the recording/playback equipment. I've had same issue above happen with my personal zip drives, and even with minidiscs.
It is also the reason I prefer to archive/backup on HDD's. The drive and heads are always aligned because they are built into the same enclosure. As long as I have an interface that can connect to the drive (currently SATA/SAS) I don't have to worry about misalignments, and so far the commonly mentioned failure modes of drives used for backups (e.g. stuck bearings) has not happened once.
Saying that, a lot of companies now just "back up to the cloud" so I don't think many even bother thinking about it anymore, but during the 2000's and before it was still an issue that many SME's had to think about. Probably why "Cloud" became so popular, as they didn't need to worry about this, or even need an IT employee anymore.
(Score: 2, Interesting) by pTamok on Monday December 01, @07:37PM (1 child)
Heh. Basement floodings are commonplace.
How about flooding an umpteenth floor data-centre in a high-rise office building*? That wasn't my story, but one I read. I thought it was in the The RISKS Forum Mailing List [seclists.org], but I wasn't able to find it the last time I searched for the source. There are some humdingers in that list.
As for 'backing up to the cloud', if your business relationship with the cloud provider fails, you lose access to the backups. This is generally not good for business. Similarly, there are various technical failures that can give you a really bad day. It's always DNS, unless it is a lost encryption key.
*Grundfos: Water distribution in high-rise buildings [grundfos.com]
Olympian Water Testing: Why do Tall Buildings have Water Towers on their Roofs? [olympianwatertesting.com]
(Score: 3, Interesting) by aafcac on Tuesday December 02, @04:22PM
I used to work security in a highrise where one of the standpipes storing water for the sprinklers had broken. That was before my time, but one of those systems can flood an area with an almost unimaginable amount of water in a matter of a few minutes if it breaks. But, a more common issue is for just one or a few of the sprinkler heads to start dumping water because they got triggered.
Water damage as you suggest is the biggest source of property damage in this context. Between plumbing disasters, literal floods and storm surges it's a lot.
My slightly off-site backups for the largest files I have go into a water resistant ammo can. It's not perfect, but if the sprinklers in the storage area do go off, it's good enough for that. If I were storing them there longer term, I'd probably throw a few desiccant packets in with the drive and use my vacuum sealer without the vacuum to seal it off. Which is fine, as that might be an issue in case of a fire, but if it's a fire hot enough to melt the vacuum seal plastic in a problematic way, it's likely hot enough to destroy the disk.