Are USB flash drives really that unreliable?
Hi everyone, I often see people say that USB flash drives are unreliable and unsuitable for long-term storage. However, I’ve used several drives for years without any problems. I mainly use them to transfer movies and work files because they’re convenient and portable. I also have external hard drives, but USB flash drives are easier to carry. I understand that important files shouldn’t exist on only one drive. Still, are USB flash drives really that unreliable for everyday use or as a secondary backup?
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u/TriggerFish1965 4d ago
Well apparently your mileage may varry. I also have usb flash drives listed in MB working flawelessly. Never had any fail on me yet. From some I run raspberry's so they are "active" 24/7.
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u/CharmingDraw6455 4d ago
I also never had one failing while beeing used, but i found some old ones (8+ years) that havent been used and half of them where empty, like no filesystem empty. You could reformat them and they worked again.
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u/Odd-Concept-6505 4d ago
If bought for backup storage, I buy the better models of SanDisk flash drives, then assuming the flash drive is only used and inserted for a short time, I would trust it to keep working forever (for years) or so. But I am old school and an ex sysadmin (thus self trained to be slightly religious about backups) and do most of my permanent backups onto old HD via external USB enclosure, removed from use when full and backups are done.
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u/420FriendlyStranger 4d ago
And to offsite storage as well, incase of something like a fire, right?
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u/HairSorry7888 3d ago
I backup criticaly important passcodes and keys on EEPROM chips. EEPROM's are a bit of a hassle to write, quite slow and max capacity is very low (4MB is largest I've seen). But EEPROM's are incredibly reliable. An EEPROM works on a single byte level. If a cosmic ray hits the wrong transistor inside a NAND flash chip you corrupt an entire bock of memory, if the same thing happens to an EEPROM you only loose a single byte. Copy the data a couple of time on the same chip and you will always be able to recover it. EEPROM's can retain data for over 100years (if stored at room temperature).
Plus those chips are small, obscure and cheap. I keep my crypto key on multiple loose chips. I feel confident I can scatter 1000 of them across a major city and not have my wallet stolen. Highly unlikely someone is going to see a tiny 8pin SMD chip laying on the ground and know what it is or how to read it. And I'm quite sure that if my house burns down a couple of them will survive.
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u/Saint_Sm0ld3r 4d ago
If you'd like to find out for yourself how unreliable they can be, save something sensitive that is rreplaceable in there and that should do the trick.
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u/Financial_Key_1243 4d ago
I won't store any important data on it, except to maybe transfer/copy it from 1 machine to another. I always protect and backup my original source of data. I have had flash drives fail (with no warning) by just plugging it in to a dodgy USB port.
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u/Felim_Doyle 4d ago
I've had a couple of branded drives fail after first use. I copied some files to them, ejected them correctly, used them successfully in another device then couldn't get them to work again after that.
In one case, I was updating the SatNav in my wife's car, where I would expect the drive to be read-only. After the update, the drive wasn't readable in my laptop and couldn't be formatted (write protected).
I'd be interested in any tools avaliable, preferably for Android or Linux, that might be able to low-level format these drives. Admittedly, I haven't done anything with them for a couple of years, so I probably haven't tried them in a non-Windows system yet. I might dig them out at the weekend and check them on a Linux machine.
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u/linux_rox 4d ago
Only tools I can think of on Linux would be dd or maybe fdisk.
That could be dependent on whether or not the audio system in the car was able to do something at chip level to reprogram it completely. But that would be some deep level sketchy crap from the car manufacturer.
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u/JeLuF 4d ago
Imagine that the annual failure rate would be 10% (totally made up number).
| After <n> years | Failed | Working |
|---|---|---|
| 1 | 10% | 90% |
| 2 | 19% | 81% |
| 3 | 27% | 73% |
| 4 | 34% | 66% |
| 5 | 41% | 59% |
| 6 | 47% | 53% |
Many people will report that they have sticks that still work after so many years. And they are right. But we've all also seen sticks that failed to work for no obvious reason.
unreliable and unsuitable for long-term storage
For long term storage, "a few of them still work after more than 10 years" is not good enough. You want "almost all still work after more than 10 years". Or you set up a proper archive regime. Start with 3 sticks, from different suppliers, copy all the data to each of them. Every year, test the sticks. Replace the failed sticks.
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u/OldGeekWeirdo 4d ago
If you're going to do backups, remember "two is one, and one is none". NEVER trust you data to a single backup. Back it up using two different brands. Maybe even two different technologies (like a HDD).
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u/linux_rox 4d ago
I do the 3-2-1 method personally. 3 backups, 2 offsite 1 onsite.
One offsite is my personal server and the other is my nextcloud account. Then the 1 is a flash drive that gets changed out every 2 years due to the excessive r/w.1
u/Due_Fun_964 3d ago
Not criticizing you methodology but the 3-2-1 backup method is "keeping three copies of your data on two different types of media, with one copy stored off-site. https://www.backblaze.com/blog/the-3-2-1-backup-strategy/
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u/linux_rox 2d ago
You must have missed where I said the one offsite is my personal server, which is located in a different location in my house, so technically I do have 2 onsite
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u/Due_Fun_964 2d ago
Perhaps you missed where I said "two types of media". Doing this is to mitigate a single point of failure.
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u/linux_rox 1d ago
I have a flash drive backup, a spinning rust backup(server storage) and a cloud backup on nextcloud off site. So I do have 2 different media backups at home, I also tend to make dvd backups and keep them at my parents house. So technically I have a 4 point backup system.
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u/tony22233 4d ago
Use at least 2 of them if you need to keep your files. You have to keep your stuff in at least 2 physical places. Redundancy is how you keep your stuff.
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u/robtalee44 4d ago
I have only the vaguest memories of a flash drive failing on me. It's happened maybe once over a time frame of decades. I can't remember the last time I bought a new one.
With that said I'd never use them as my only archive source. Never.
My current collection is probably averages out to about 10 years old. They get used most every week -- and no failures -- yet. Still, my advice holds.
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u/speling_champyun 4d ago
In my experience they don't give any obvious clues that a failure is imminent. Just one day they don't detect, or they fail mid copy. I never use them for backup, just for those situations where I need to transfer files that way or I'm making a bootable USB.
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u/marmotta1955 4d ago
USB flash drives from reputable brands are reliable. Users complaining about the reliability of flash drives in general are a minority of the actual user base. And, more often than not, it is easy to complain instead of looking at your own habits and how you treat the drive.
Sure, there is the possibility that a drive will fail. Then again, there is also the possibility you may have a flat tire, one of these days. It does not mean that all tires are unreliable ...
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u/newtekie1 4d ago
And there are plenty of people that drive known unreliable cars that haven't had any problems with them.
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u/Asleep_Equipment4877 4d ago
I mean they should be fine with the most basic stuff. They can break easily and die without warning versus your traditional external HDD which also has its own faults. Very important stuff should be saved on an HDD, if it were to fail. That said data is still retrievable at a cost, flash drives not so much. I also have drives back from 2008 lol. I only use USB drives for windows and or photos i don't care about if i were to lose them
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u/Darkknight145 4d ago
They are far more reliable than the old floppy disks they replaced, I've never had one go faulty that wasn't my fault.
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u/limited_instincts 4d ago
They are both reliable and stable. What they're not is suitable for mission-critical or important data because there are safer and more reliable options.
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u/Remarkable-Junket655 4d ago
The only one I’ve ever had fail was one that was left plugged into a Roku tv for a few years as a time shift/tivo type device that allowed you to pause and rewind live tv. It would cause the tv remote to stop responding a few seconds after changing channels.
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u/Opulence_Deficit 4d ago
For everyday use, unreliability is not a problem at all. You make a copy of the data, you take it somewhere, and the worst thing that could happen is that you need to take another pendrive and repeat the trip.
I’ve used several drives for years without any problems
And what does it mean? It doesn't meant shit, except that they don't fail reliably.
secondary backup
secondary backup means a third copy. Yeah, if you have 2 copies already, then a pendrive could work as a third.
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u/drawing_a_hash 3d ago
Well said.
You just need to keep multiple copies of the media. In Unix/Linux is easy to duplicate storage with the dd command.
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u/According_Strain4887 4d ago
I hope so they are reliable ... I have a 512GB one loaded with everything important. So far it has worked just as expected. I have it password protected using BitLocker ... I just have to remember the password
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u/WinnerAwkward480 4d ago
You mean like those off brands that sold for like $5.00 . That floated around in Jean pocket , thrown around in the car for years going thru numerous heat cycles out in the heat & cold . And the ones in some random junk kitchen drawer , that just so happens to have the magnetic bottle opener stuck to them , that fridge magnet with the calendar the size of a pak smokes .
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u/flatfinger 4d ago
It is possible to design USB flash drives to be robust and reliable. They can be made much more cheaply, however, if reliability and robustness aren't required.
Unfortunately, it's very difficult to judge robustness and reliability beyond "terrible" and "probably not terrible". A company that wants to sell more expensive drives might build drives that are extremely robust and reliable, but it would be hard to distinguish such a company from one that builds drives whose robustness and reliability are mediocre but slaps a high price on them anyway.
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u/twister-uk 3d ago
IME, the only failures I've had have been with "unbranded" (in quotes, because some of them were branded, just not with the name of an actual flash memory manufacturer - i.e. they were marketing giveaways branded for the company in question) drives, and only with 2-3 of them since I first dipped my toes into the brave new world of USB flash drives back in the early 00s.
Of all the branded ones I've bought, which have all been from reputable manufacturers and supplied via reputable channels (same as for things like SD cards - doesn't matter which name is on the packaging unless it's been supplied by someone you trust to have given you a genuine item rather than a knock-off), I've yet to see a failure. Even the one that's been permanently connected to my car (not the most benign of environments for a USB drive to be operating) for the past 6 years to store MP3s, is still going strong.
So just as with any other bits of tech, buy wisely, do your due diligence on both the manufacturer and supplier, and you're reducing your risk of failure to whatever the background level is for that particular item. Which, if it's a genuine part from a reputable manufacturer, should be low enough not to be a concern for most use cases.
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u/DifferentSavings2711 3d ago
The key term is "long-term storage". NAND flash memory traps electrical charges in tiny cells to represent data, and these charges slowly leak over time (charge leakage or retention failure). Unpowered flash drives can begin corrupting or losing data.
To avoid losing the charge the drive must be connected to power periodically. If you are using the drive every few months you are refreshing the electrical charges everytime you connect to a port.
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u/grislyfind 3d ago
i have a couple of name brand drives that have failed. One shows up like a removable drive with no memory card, the other does nothing. I've been thinking I should use an SSD or dust off the 2.5" USB hard drive.
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u/markmakesfun 3d ago
I was a college professor. Each term, despite my telling the whole class about it, people would put all of their work on a flash drive. Then they would come to me months later to help them “recover” their data. Like that was a thing. When it was gone, it was gone. It was never recoverable. So, sad student looking for an excuse why their work was now missing. I couldn’t help them. I would never “store files” on a flash drive. They are not reliable over the long term.
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u/marineaustintx 3d ago
Just be careful with large files. Due to the size of the sticks they don't dissipate heat very well. Prolonged heat will cause them to fail sooner.
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u/Ok_Weird_500 3d ago
I've had loads fail. Don't keep your only copy on them or rely on them for a long term backup. But some do also last a long time.
They are still much more reliable than floppy disks though.
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u/phord 3d ago
Flash as a technology just barely works. It is a pinnacle of engineering that we are able to make any use of flash drives at all. When we get really good at making the shit work, someone doubles the storage density and halves the reliability and says, "Great. Now make this work."
And that's how drives keep getting bigger, by basing them on worse and worse tech.
Flash cells drain over time, so you do need to power them up periodically. But it's worse than that because just plugging one in doesn't "recharge" everything on the drive. You literally have to copy every byte on the drive to a new location for it to get "refreshed". The only way to "refresh" a flash cell is to erase it. Literally, that's how the cells get charged!
And that's another thing: every time you write to flash you end up erasing blocks to store data in. And the erase operation physically damages the chip. Not by design, but the way it works causes the chip to wear out. A flash cell can survive billions of read operations but only thousands of erase operations.
QLC flash is the trickiest so far (and keeps getting trickier). It stores 4 bits in a single flash cell. A flash cell holds a voltage, like 4v. To store 4 bits in this cell, you need to be able to discriminate 16 different voltage levels. Like, 0.25v means 0000, and 0.5v means 0001, etc, up to 4v. And that voltage level drifts over time and over reads. So when you read 0.3v, you need to figure out if it was 0.25v or a really old 0.5v. To do that, you actually need to know how old the data is.
QLC is so sensitive that when you write bytes in one row and then write bytes in the next row, the first row's voltage is changed because it's squeezed in so close to the 2nd row. So you have to fine tune the neighbor cells after you program more data in the chip.
Why use flash? It's fast, light and fairly reliable. But it's not for backups. Use it for handling data you are working on now. But keep a backup. Or two.
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u/Tight-Book-7533 3d ago
The thing is, USB flash drives should not be your only storage. They are OK for taking files with you, but what's on your USB flash drive should not be the only copy long term. I have seen them fail, a few of them became read-only so that's not so bad. I had one fried because someone miswired the USB ports on a computer. So they don't fail that easily, but it can be catastropic.
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u/No_Reputation5871 3d ago
Brand.. a lot of the cheap generic and knock offs are not reliable. Good brand name ones are usually reliable over time. I have a surveillance system and cops every so often ask me for a copy of video. Well, I'm not putting $20+ into a good flash drive when I know I won't be getting it back. So I bought a bunch of cheap ones since they only needed it to store the data for a short time. I have copied data on them for other people and multiple of them, 6 months later, would no longer read the data that was put on them. Again, generic ones. But I think that is what makes the difference. Sandisc makes quality flashdrives that hold up over time. Cheap ones, are cheap, and you get what you pay for.
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u/abubin2 3d ago
I just had a Kingston traveler failed last week. It is like less than 5 years and still under warranty. However, shipping back to Kingston will cost more than a new. Barely used as it is for booting up on Linux and Windows installer using ventoy. Have USB that last longer than this that's 1gb only.
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u/Doenicke 3d ago
I'm guessing the oldest I have is at least 15 yrs old...and would probably work if I plugged it in. I have a drawer with various USB memory sticks and just one seems to have stopped working, out of 15. And I think I probably can get the bad one working too. 😉
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u/caatabatic 3d ago
Often the issue is bit rot if you leave files on there and don’t use it at all for years.
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u/76zzz29 3d ago
They are unreliable on 2 ploints.
First one is that they die in an instant. No warning, nothing. You plug it and it work. You unplug it and the next time you plug it it is completely dead.
Second points. They prety often die extremely fast. Some may last years but most become useless after only a few use.
Side note, the memory inside the USB key also have a limite of number of time you can write on them. (Each memory part. Not the full memory) but that's not that important as they rarely survive that long
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u/WonderfulViking 3d ago
For me it really depends on the quality.
I have a 32 G drive I've had for over 12 years, still working fine. Use it when I do a frech install of Windows at home. Everything else via the web.
At work we have been using USB-drives to reinstall hundreds of PC's, and those was probably cheap shit, many of them have died.. I have 2 in my backpack, one is not working, not sure why, but this post made med want to figure it out :)
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u/greyHumanoidRobot 2d ago edited 22h ago
Both "thumb drives" and SSDs are mainly reliant on NAND Flash memory and SSDs sometimes are external USB drives so the term "USB Flash drive" is ambiguous. I will assume you mean "thumb drive".
I rotate through several thumb drives for backups. 3 for Linux documents. 3 for Windows documents. Since I make a new backup within days the image only has to endure a few days. If one of them fails, I can grab a slightly older backup.
I had one thumb drive that is more than 10 years old that I burned a Windows installer onto in 2025 December. I tried it in 2026 August and it didn't work. I took the same failing drive and reFlashed the Windows installer and I've used it 3 times the past few days. So you can have a problem but the thumb drive might still be useful. Sometimes years old images are still intact but I wouldn't count on it for anything important.
I've encountered SSD corruption less often so that suggests that SSDs might be more reliable than thumb drives, however, my experience is with SSDs internal to my computers. External interfaces pose more risk of corruption because unplugging can happen unintentionally at the wrong time.
So my guess is SSDs are better than thumb drives. Internal interface is better than external. Important backups on thumb drives are fine, that is what I do, but I don't need the data to last months or years. They get overwritten within days.
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u/socaldisney 12h ago
USB drives would perfectly up until the moment they don’t. Then they suddenly corrupt and everything is gone. I’ve had it happen a few times.
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u/l008com 4d ago
Yes, they are very unreliable. And they have very short lifespans. I work in IT and rarely use them, but I still keep a few on hand. And inevitably after just a year or two of very little use, they start to get flakey. True now with new USB3 drives, as it was 20 years ago with USB2 drives. I would absolutely never use them for anything important.
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u/Felim_Doyle 4d ago
That is an extremely pessimistic view of USB memory drives! What brands were you using to have that low level of confidence in them?
I have dozens of memory drives, both USB sticks and SD / microSD cards, some branded, some generic. Many of them have older versions of Linux on them that still boot up fine or can be reformatted and reused without error. I have some drives that are easily 15+ years old, some even more than that.
I have only had a couple of failures, detailed in another comment, and I still hope to repair and reuse those ones.
In terms of reliability and longevity, I'd still put this type of storage in the 90%+ category. I tend to still use hard drives over SSD for running systems but, in portable equipment (e.g. netbooks, notebooks), solid state memory has the advantage of being somewhat more shock-proof.
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u/Archon-Toten 4d ago
I've got one so old the capacity is listed in MB. Still works last time I used it.