Helping people with computers... one answer at a time.

Leaving a flash drive or USB thumbdrive plugged in all the time can run a risk of prematurely wearing it out. We'll look at why, and what to do.

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 upon 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 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 questions, but unfortunately very tough questions to answer.

Flash drives do wear out, absolutely.

But exactly when a flash drive will wear out can vary based on so many things it's almost impossible to give a specific answer.

I'll give you my best guess answers, and then also throw out some guidelines that I'd follow on using a flash drive were I in your shoes.

First I'll answer your questions, in reverse order:

What wears out? You're correct, there are no moving parts, but there are electronics. The type of electronics that are being used in flash drives actually wears out a little each time something is written to it. Eventually attempts to write further can be lost because of that wear.

Perhaps the best analogy I can give you are old style CRT screens at airports and in cash machines that display essentially the same thing for months on end. Eventually, the coating underneath the glass display wears such that even when the device is turned off you can see a ghost or pattern of what had been displayed there before. This is called "burn in" and is the reason that screen savers were invented. Eventually that ghost can become so prominent as to interfere with the readability of whatever is displayed when it's turned back on.

"It's always important practice to have at least two copies on different media of anything important."

Flash memory doesn't really "burn in", but it does wear in a conceptually similar way.

Why "Safely Remove"? In an effort to make accessing the device faster, Windows may "buffer" data before writing it to the actual device. Safely Remove forces Windows to flush everything to the device. NOT doing so, but just yanking the device out without warning, could then cause the files - or worse the file structure - to become corrupt and unreadable.

Writes to flash memory are expensive (slow) and as we've seen causes wear. In addition, writes only happen in multiples of the sector size - typically 512 bytes. So let's say you write 100 bytes of data to the device, wait a while, and then write 100 bytes more. There are two approaches:

  • Take your 100 bytes of data followed by 412 bytes of anything and write that into a 512 byte sector. Then on the second request read the sector back in, add the next 100 bytes of data following the first 100 bytes, and write it back out.

  • Place the 100 bytes of data into a 512 byte buffer in your computer's memory or RAM. When the second request comes along add the next 100 bytes. Later when the file is closed or more data is added to fill the sector completely, write the data you've collected.

As usual that's a gross oversimplification to make my point, but as you can see the first scenario has three operations to the device: a write, a read and a write, whereas the second has only the single write. The optimization is simply that writes to the device are delayed until they are necessary. This maximizes speed and minimizes the wear on the device.

Safely remove simply makes sure that any partial data managed by the operating system that is waiting to be written to the device actually is. In addition, it also checks for applications that have files open on the device that may be in a similar partially-complete state.

Should I leaving it plugged in? This is where "it depends" really comes into play. And the problem of course is that it depends on things that actually aren't all that easy for you to see.

What it depends on is easy: is the device being written to - even occasionally - while its left plugged in? I'm not talking about your work, I'm talking about other programs like your operating system, anti-malware software, utilities and other things that - on the surface - would have no reason in the world to write to the device. And yet some do. Maybe.

Me? I wouldn't. The only way to be sure is to remove the device to maximize its life.

And for the record, any time your computer is powered down - be it off, hibernate or stand-by - there's no issue. No one's writing to the device when the machine is turned off. If, however, like me you leave the machine on 24 hours a day, then there's a small risk.

So, how big is the risk?

You're going to hate me for this.

It depends.

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'd never be a problem. Heck, most people would probably lose the flash drive before it actually wore out.

And the quality of flash memory is constantly improving. High end (read: expensive) flash memory is being used to actually replace hard disks, so you know that while they still wear out their lifespan has been increased to the point of it no longer being a practical issue. But that inexpensive flash drive you picked up? It's 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. And Murphy's Law being what it is, failure will happen when it's least expected, and most inconvenient.

Mitigating the Risk

Here's what I recommend you do.

Plan for failure.

Just assume that sometime out of the blue a write to your flash drive will fail. Or that a later read from it will fail.

Make sure that through some form of redundancy - periodic backups come to mind - 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), perhaps that means you're ok losing a weeks worth of work. In any case, do something that makes sense for you.

It's always important practice to have at least two copies on different media of anything important. That's advice that's independent of, and certainly predates flash drives. Heck, back in the day floppy disks wore out too.

And let's face it - even if your flash drive doesn't wear out you could lose it, with the same potentially disastrous results.

Article C4224 - March 18, 2010 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

Brigitte Guetter
March 18, 2010 5:58 PM

Leo, I started reading this article because of a small interest in the topic, but I kept reading to the very end because once again I was, and continue to be, amazed by your exceptional clarity, anticipation of possible questions, and overall elegance of writing. Very rare and much appreciated. If I wore a hat, it would be off to you.

March 20, 2010 1:44 AM

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.

March 23, 2010 8:39 AM

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.

March 23, 2010 8:59 AM

Memory sticks are nothing more than the combination between a card reader and a memory card. It the memory card part that wears out, no matter the form , size or format.

Cathleen Caffrey
March 23, 2010 9:00 AM

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.

Network Administrator
March 23, 2010 9:06 AM

The only Flash Drive with a 10 year warranty...

Corsair - Flash Voyager®, Flash ReadOut, TurboFlash, Flash Survivor and Flash Voyager® Mini USB flash drive products all have a 10 year warranty.

Best Price...

I do not store any data in a cloud... this is why... you do not know where it is going... USA, China, India, Russia... and etc.

Per Wikipedia... "Live Mesh is a data synchronization system from Microsoft that allows files, folders and other data to be shared and synchronized across multiple personal devices"

Also there is no such thing as encrytion that cannot be cracked... if you have the time and the equipment any encryption can be cracked.

I know... you have nothing to hide... just remember... do not put anything on the internet, that you do NOT want seen in a newspaper, magazine or billboard.

March 23, 2010 11:13 AM

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..?

March 23, 2010 1:18 PM

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.

Robert H.
March 23, 2010 1:27 PM

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.)

Pikson A
March 23, 2010 7:43 PM

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.

March 23, 2010 7:47 PM

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.

March 24, 2010 3:40 AM

“Would it be foolish to store something like photos on flash drive and expect them to be retrievable years later?"

Flash drives work by placing an electric charge onto millions (well, billions) of tiny pieces of very well-insulated material (the charge is induced there - first the nature of the insulation is electrically changed, then a high voltage is placed nearby which sucks the electrons out - cleverly creating a positive charge on a piece of material inside an insulated container).

If the insulation was perfect, the charge would last forever and your data would be safe forever. But there is no such thing as perfect electrical insulation, therefore the charge will leak out over time.

Over what time? That depends of course - but between a few years and 10 years is probably about the likely useful life of any one charged bit. After that its charge may have dropped below the threshold that marks it as a one not a zero - and your data is irreversibly destroyed.

(Clay tablets are the current best long-term storage option for data, and cave walls for images) :)

March 24, 2010 6:09 AM

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...

Ravi Agrawal
March 25, 2010 2:14 AM

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.


Tom R.
March 28, 2010 11:50 AM

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.

Carlos Coquet
April 13, 2010 1:59 PM

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 !!

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