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Is It Safe to Leave a Flash Drive Plugged In All the Time?

Some time ago I think I read on your site that flash drives can wear out. Now, I keep my flash drive in all the time because I’m a writer and am always backing things up on the computer and the flash drive, but I dislike having to close the flash drive down, take it out, only to reinsert it again after I take a break or run an errand. And I always leave it in when I run a full system scan because the flash drive will get scanned also.

1. Is it harmful to the flash drive to just leave it plugged in 24/7, even when I put the computer on standby for the night?

2. Why is it necessary to shut the flash drive down before removing it from the computer? Why can’t I just pull it out when done?

3. And if I am correct about flash drives wearing out, what wears out? As far as I can tell, they have no moving parts. And at what point should I consider replacing the flash drives I have?

These are very legitimate, but unfortunately very tough, questions to answer.

Flash drives do wear out, absolutely.

But exactly when a flash drive will wear out depends on so many things, it’s impossible to give a specific answer. All I can say is “It depends.”

I’ll give you some guidelines that I’d follow on using a flash drive, were I in your shoes.

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What wears out?

You’re correct: there are no moving parts in a flash drive. A flash drive is so named because it uses what is called “flash memory” — a type of solid state memory that retains its contents even after power has been removed.

These devices wear out a little each time something is written to it. Write to it enough, and eventually writing to it will fail.

Exactly how quickly this type of failure happens depends primarily on two things: the quality of the electronics and the number of writes. SSDs — solid state drives — are also a form of flash memory, but they’re now of high enough quality that they often outlast the computer they’re in, under normal usage.

External USB flash or “thumb” drives? Not so much.

Why “safely remove”?

Questionable USB Drive In an effort to make things faster, Windows may “buffer” data before writing it to a device. That means if you pull the device out at a random time, even though it might look like whatever you’re doing has completed, it’s possible not everything has been written. In the worst-case scenario, that could corrupt the information that tracks what’s where on the device, and cause you to lose files and data.

While it applies to both flash drives and traditional magnetic hard drives, writing to a flash drive is also slower than reading from it, so there’s a performance benefit to buffering as well. Delaying writes until they are necessary maximizes speed and minimizes wear.

The “Safely Remove” function forces Windows to flush everything to the device. In addition, it checks for applications that have files open on the device that may be in a similar partially-complete state.

Recent versions of Windows have changed their default behavior such that write caching isn’t used as much as it was in the past, so “Safely remove” may not be needed on all of your USB devices.

Should I leave it plugged in?

This is where my “it depends” really comes into play.

What it depends on is easy: is the device being written to — even occasionally — while it is left plugged in? I’m not talking about your work; I’m talking about other programs, like Windows itself, anti-malware software, utilities, and other things that — on the surface — would have no reason to write to the device.

And yet some do. Maybe.

If your computer is powered down — be it shut down, hibernate or stand-by — there’s no issue. Nothing’s writing to the device when the machine is turned off.

If, however, like me, you leave the machine on 24 hours a day, there’s a small risk.

Risk? How big a risk?

It depends on several things.

It depends on the quality of the flash drive. It depends on what software you have installed on your machine. It depends on how your USB or other connecting port is configured (some of the buffering might be turned off). It depends on how long you plan to keep your flash drive. It depends on how catastrophic it would be to you if it failed.

For many — perhaps even most — there’ll never be a problem. Most people might physically lose the flash drive before it wears out.

And the quality of flash memory is constantly improving. As I mentioned above, high-end flash memory used in SSDs have a practical lifespan that will probably be longer than the machines in which they’re installed.

But that inexpensive flash drive you picked up or were given for free? It’s probably not going to be that same high quality. In fact, where it’ll be on the quality scale — a scale that is constantly moving — is anyone’s guess.

But the risk is definitely there. Murphy’s Law being what it is, failure will happen when it’s least expected and most inconvenient.

Mitigating risk

Here’s what I recommend you do: plan for failure.

Assume that sometime, out of the blue, a write to your flash drive will fail. Or that a later read will fail.

In fact, that’s an assumption you should make about any storage device you use. Traditional hard disks also fail, often completely and without warning.

Make sure that through some form of redundancy, you can recover to a convenient spot.

Perhaps that means you need to save two copies every time (one to your laptop, one to the flash drive). It sounds like that’s exactly what you do.

Perhaps it means that you don’t use a flash drive at all, but rather an online storage service like Dropbox, so every time you save the file it’s updated online. That’s my preferred approach these days.

Perhaps it means deciding beforehand that it would be OK to lose a weeks’ worth of work.

Regardless of which it is, make it a conscious decision and then act on it appropriately.

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Footnotes & References

1: Also often referred to as a “USB stick” or “thumb drive”, as that’s often about how big they are and what they look like.

31 comments on “Is It Safe to Leave a Flash Drive Plugged In All the Time?”

  1. The person could use Live Mesh or Dropbox for automatically backing up documents online. These services are pretty much replacements for many of the things I used to with flash drives.

    These services transfer data via https, however, I am not sure whether they also store in encrypted form. One can use 7-zip etc for that, I suppose.

    Good suggestion, assuming there’s an acceptable internet connection in all cases. I happen to use Evernote to the same effect. I do believe that they store data encrypted, but it’s always wise to be cautious if you’re not certain.


  2. I just finished reading your info on flash drives and found it interesting and informative. I use a small 4 GB SD card in the card reader in the side of my laptop to store backup info. Is this affected the same way as a flash drive?

    Yes, flash memory is flash memory regardless of the package it’s in. USB sticks, SD memory cards, CF memory cards all use flash memory.


  3. Would using an external hard drive solve some of the wear and tear concerns? i.e. are they longer lived and sturdier?

    My knee-jerk reaction is to say yes, but as always it depends on the quality of the hard drive and how else it’s used.


  4. Your info on “you write 100 bytes of data to the device, wait a while, and then write 100 bytes more”. The answer is out of my realm, it sounds very time-consuming etc to know how much you’ve written (100 bytes-huh?) These Memory cards are so cheap, isnt this going a little beyond reason? Just buy a new one every year..?

  5. I think the person who asked the original question is really barking up the wrong tree. He mentions constantly “backing-up” to a flash drive. These drives should not be treated as a “back-up” medium. They are really only meant to be used as a convenient means of transferring files from one computer to another, like the old-style floppies. Permanent storage they ain’t! Other methods should be used, such as an external hard drive. I actually use three – bit OTT, I know but can’t be too careful with around 80 gigs-worth of irreplaceable music and data.

    • You wrote, “Permanent storage they ain’t!”

      Not quite correct. Writing data to a flashdrive causes “wear & tear” to its flash memory, but reading data from a flashdrive causes no stress to its flash memory at all — so it is perfectly reasonable to write files to a flashdrive, “safe remove” it, then physically store that flashdrive as a form of backup.

      Hope this helps…

  6. Does this wearing out problem exist for stored data that’s not being rewritten? Does reading data from such a device cause it to be removed and rewritten? Would it be foolish to store something like photos on flash drive and expect them to be retrievable years later? It’s not clear to me whether age alone, absent constant use, might lead to failure.

    While the data itself might not be written to, the filesystem – the information that allows the data to be located – will be written again and again, and could lead to loss of the files. Yes, in my opinion leaving important data on only a single device is a bad idea, and especially bad if that’s a flash drive that’s in use. (I have no idea what the risk might be of a flash drive that’s not in use, but I personally would not trust it.)


  7. I’ve faced this problem before; about the flash drive wearing out and its true, though the flash doesn’t have any mechanical moving parts like the old time hard drive it still will wear out as you write data to it continuously. Flash also need to be kept away from moist and dampness as this will cause it to lose data. So it quite depends on how you look after your flash.

  8. Hi, Leo.First of all, Thanks for all the so perfect useful answers you gave me all the time. I looked for video cards, didn’t find, so if I am posting the wrong place, please forgive me.
    My PC has Intel Core Duo T2300.My question:
    Is it possible to change a Intel PC video card for a Nvidia Geforce 4 or FX series cards?
    I need it to play Civ4, The Sims2 and other huge games.Thanks again, I do appreciate your help.
    You can change this question to minimize it or change its place.Sorry for that.

  9. Maybe I’m missing something, but surely the whole point of backing something up is to protect the data from any loss – for example a house fire, flood etc – in a kind of “disaster recovery” situation.
    In this case wouldn’t it be better to save to the flash drive, but then remove the flash drive and store in a separate location – in your pocket perhaps – that way if the house does catch fire etc, you can protect your data from loss…

  10. What about the Heat. They do get hot when in use. Hot things deteriorate faster.

    So I guess, use when needed.

    Plus one more thing. Every time you save a file, the old file is being deleted and a new one is being written. Keep that in mind. Use your Harddisk instead. Copy the final version to the Flashdrive when done.

    If comfortable & if you have the previlige of an always ON internet connection, use google docs.

    No worries, then.


  11. Flash drives do wear out but are also remarkably robust. I took a load of laundry out of the washer once to find my flash drive lying in the bottom of the tub. Oops!

    I crossed my fingers, set the device aside for 24 hours and plugged it in.

    Voila! It worked perfectly. All of my files were still intact. I’m still using that drive 2 years later.

    I now faithfully check all of my pockets before loading the washer.

    • Tom R here again. That 16 GB thumb drive I accidentally laundered in 2010 is still faithfully doing service as a go-between from my main rig to transfer files to my PlayStation for display on my HD TV. Some things just won’t die. I think it cost like 40.00 dollars back in the day. Go figure.

      • I once washed a couple of USB flash drives in a washing machine (don’t try this at home) and they lasted for years afterwards. They didn’t go through the dryer. I suspect the heat would have damaged them. Now I always check my pockets twice before washing now :-)

  12. Because they are so easily lost, I consider flash drives strictly for backing up and/or transfering data. On that subject, most people think of “backing up”

    as just copying stuff from one place to another. While that is better than nothing, it is often NOT enough. Traditional backup software creates a file in

    which it places all the files being backed up. This allows having many copies of some data in the same “volume” (like a single flash drive). If one is only

    dragging and dropping stuff instead of using a “traditional backup program” then it is wise to create a directory (folder) for each backup, giving that

    directory (folder) a new, unique name, such as the date and time the “backup” is being created.

    The advantage of this approach is two-fold: in the vein of information in this article, is spreads the utilization of the flash drive’s surface. Each backup

    uses a different area of the flash drive. Additionally, and more importantly, it creates multiple versions of the files being backed up (one in each

    directory). This is important because sometimes we may either want to “drop back” to a certain date, or retrieve a deleted file or data, or investigate when

    a certain problem started. Some data program may have started losing or corrupting data some time ago. Those who backup to the same area (or

    directory) over and over, they have only “one round” before both their original and their backup are identically corrupted.
    And yes, I recommend my clients keep the backup and the original data (usually in their computer) far from each other, the backup ideally offsite.

    Saddly, few heed such advise and they will contribute heavily to my standard of living when things go South !!

  13. I found another consideration when saving to a flash drive. Windows 10 now protects some file locations from ransom ware by not allowing write operations to them. USB ports can be in this category. If you have this protection enabled you can’t write to it without disabling the protection or some other similar action like administrative permissions. (Some users use their computers with administrator accounts and some with standard accounts) This doesn’t make it impossible, just inconvenient.

  14. I use flash memory mainly as temporary storage, for example, to transfer files from one computer or device to another. I also use it in my phone but I keep my phone files constantly backed up. The bottom line is: if you use flash memory for anything but temporary storage, make sure is has a couple of backups or more. Another issue resolved by backing up.

  15. If you’re (unprotected) flashdrive gets encrypted because your computer gets infected by ransomware, you’ll regret having the flashdrive inserted permanently.

  16. Eh; in theory you are right. In reality I have used only flash drives (aka USB drive); (as I do not like anything to be stored in my computer hard drive). So we are talking using 24×7 over some 25 years, of cheap flash drives (yes, I still use some of them old ones). No failure of the flash drives, never. I do not think this is because I am lucky (I am not). Sometime I get a corrupted file which I can’t open (Later on), but I think it has nothing to do withe the flash drive, but the Windows OS.

  17. It seems strange that a flash memory drive should wear out, since as many have noted, there are no moving parts. The reason why this happens is that flash memory consists of millions of tiny cells which consist of a conductive core surrounded by a thin insulator. Flash memory works by blasting electrons through the insulator into the core. The electrons then stay trapped there because of the insulation. (This is why flash memory is non-volatile — that is, the data stays put after the power is turned off.) But every time the electrons are blasted through the insulation layer, it damages that insulation slightly, causing it to degrade over time.

  18. My old laptop had an SD card slot. I put a good-quality SD card in there and used it as a ‘boost’ location (I forget the exact name of the feature).
    USB flash memory does wear out – I once read an (extreme) case where someone assigned a USB stick as page / swap file memory, to see what would happen. The stick failed completely after about 8 hours.

  19. I use four sources to save and back up. One on the computer hard drive. Two on an external drive, which also has online back up. And three auto back up to an online storage site which is well worth the hundred dollars or so should disaster strike and all is lost. And Third on the most least trusted; Flash or Thumb drives. I have had several Flash/Thumb Drives go corrupt and become unreadable and nonrecoverable. Same with CDs and DVDs. I have had Hard Drives suddenly start burning out and had to be replaced ASAP. So there is no one technology that is 100% incorruptible. One of the best lessons I learned from a computer tech instructor in college was; back up , back up, back up. At least three sources. He called them son, father and grandfather :) I also still keep a hard paper copy of really important files and documents stored in a brief case that I can grab and run out the door with in an emergency. I have my photos stored on two Web Albums that I share with a couple of family members so they have access to them in the event that I lose access. Might be overkill but in the past I lost many files and photos due to MS Windows crashes and files becoming corrupt and unrecoverable. I now use Linux Ubuntu which has given me very few problems compared to MS Windows.

  20. Hello all you nice people who share information.

    My question is slightly different, I have a flash drive with movies and TV series which I plug into my flat TV screen.
    Should I un-plug the flash drive when I stop watching movies? It does get hot.


  21. I’m sad I didn’t read this before my USB failed. Nothing critical on there but I would love to get the documents back – is there any way of doing that?

  22. Flash memory is very cheap now-a-days. My only concern is the data. Keeping several copies eliminates that risk.

    As for giveaway USB drives, “that inexpensive flash drive you picked up or were given for free, where it’ll be on the quality scale . . . is anyone’s guess.” My guess is the company that gave it away got a very low price because the drive was on the low end of the scale.

  23. More of a question, than comment. I’m stumped. Instead of paperwork, when I bought a used car I was given a flashdrive. I power up my computer, pop it in and immediately it shuts down & powers off..! Every time. I put it in , it shuts down.? What’s going on, is there something wrong ? Is it intentional by the dealership that sold me the car?? Can anyone help ??

    • That sounds just wrong. I’m torn. In your shoes, I’d be tempted to try a different computer. But honestly, I’d go back to the dealer and ask them what’s up and if they can replace it — perhaps with paper.


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