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It’s well known that USB flash drives are supposed to be ejected before removing them. Your computer will often display a scary warning if you fail to safely eject the drive. But do you really still need to do this? What happens if you don’t?

Let’s take a look.

Different Protocols

First, we need to consider three different protocols 10 Networking Terms You Probably Never Knew, And What They Mean 10 Networking Terms You Probably Never Knew, And What They Mean Here we'll explore 10 common networking terms, what they mean and where you are likely to encounter them. Read More your drive may use when connecting to your computer. Two of them don’t need to be ejected at all.

mounted flash drive

mtp-android

Smartphones, cameras and other media devices that connect via either MTP or PTP can be disconnected simply by pulling out the USB plug without any damage to its storage.

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Why Would You Need to Eject a Drive?

If your drive (or device) connects using the USB Mass Storage The Office Worker’s 101 Guide to a USB Thumb Drive The Office Worker’s 101 Guide to a USB Thumb Drive Flash drives today are not just about storing your important files: you can use them to run programs and even entire operating systems. Read More protocol then it should ideally be ejected. Although, as we’ll see, it differs slightly depending on whether you’re using Mac or Windows.

This applies even if you’re not actually using the device at the time.

The reason is because operating systems use a process called write caching. The operating system doesn’t always write a file to a drive immediately, but instead caches it and waits until it has multiple write operations to complete.

Doing these all at once improves performance, but if the cache is still full when you remove the drive, your data will become corrupted. Clicking the Eject button causes the cache to be emptied and any remaining data to be written to the drive.

That’s the reason why there’s often a delay of several seconds between ejecting the drive and being notified that it’s safe to remove it.

There are also potential issues with the abrupt removal of the power supply from a flash drive. Flash memory is susceptible to this, and it can cause parts of the drive to become corrupt.

Ejecting a Drive on a Mac

All this information applies to flash drives plugged into Mac computers, and to Linux machines as well.

These use write caching to deliver superior performance.

Ejecting a drive on a Mac is a simple process. Just drag the flash drive icon — that will have appeared on the desktop when you first connected it — into the Trash. Or click the Eject icon next to the drive name in a Finder window.

ejected flash drive

Ejecting a Drive in Windows

The situation with Windows is slightly different.

By default, Windows has write caching disabled. This results in slightly inferior performance when writing to the drive, but also adds a layer of security to the many users who forget to ever eject them.

If you’re not concerned about the risks, you can activate write caching on drive-by-drive basis.

To do this, locate the Device Manager on your PC — Control Panel > Hardware and Sound > Hardware and Printers > Device Manager on Windows 7; or right-click in the bottom left corner of the screen and choose Device Manager on Windows 8.

windows-write-caching

Right-click on the attached drive, click the Policies tab, change the removal policy to “Better Performance”, and enable write caching setting accordingly.

If you do this, you will always need to ensure you eject the drive via the Safely Remove Hardware option in the system tray.

safely-remove-hardware

And just to note, write caching is already enabled on internal drives by default and you shouldn’t disable this as you will notice a significant drop in responsiveness.

A Quick Word about Hard Drives

So far we’ve been talking about flash drives. If you’re using an external hard drive then you should always eject it before you disconnect.

external-hard-drive

Most modern external hard drives will also be powered over the USB connection. Cutting the power while the drive is in use could cause a head crash Hard Drives, SSDs, Flash Drives: How Long Will Your Storage Media Last? Hard Drives, SSDs, Flash Drives: How Long Will Your Storage Media Last? How long will hard drives, SSDs, flash drives continue to work, and how long will they store your data if you use them for archiving? Read More .

This is where the head, which swings back and forth just above the spinning disk to read and write data, comes into direct contact with the disk and causes physical damage to it.

This can render large chunks of the disk unusable, or even the entire drive. Learn how to properly care for your hard drives How to Care for Your Hard Drives and Make Them Last Longer How to Care for Your Hard Drives and Make Them Last Longer Sometimes an early death is the fault of the manufacturer, but more often than not, hard drives fail earlier than they should because we don't take care of them. Read More .

Wrap-up

So, to summarise, media devices don’t need to be ejected. Neither do flash drives on Windows, unless you’ve specifically changed the settings for them. Drives on Macs should always be ejected, as should hard drives.

Improper removal of drives could cause data corruption, or in worse cases, put the integrity of your drive at risk.

Do you always eject your drives before unplugging them? Have you ever suffered data loss or other problems as a result of not doing so? Let us know in the comments below.

Image Credits: External hard drive via Karen

  1. Donna
    April 1, 2016 at 2:10 pm

    This may be a silly question, but… I know if a disk is improperly disconnected, that can cause corruption on that disk. But can it cause problems with the computer as well, such as with the file directory? And if it did cause problems with the computer, would those be limited to how it relates to the disk in question?

  2. TJ Avatarici
    March 17, 2016 at 9:16 pm

    Dear Microsoft: Fix me, Seymour, fix me !!!

  3. Bham Scot
    February 26, 2016 at 3:35 pm

    Thanks for the explanation! I've always known I should, and I've always known that it's because "data could be lost" but nobody's ever explained what's happening inside, and how that affects the eject process. I feel so much better educated now, and it was so easy! Why doesn't anybody tell you this!?

  4. Kevin Buchs
    March 27, 2015 at 1:57 pm

    This statement is flawed: "There are also potential issues with the abrupt removal of the power supply from a flash drive. Flash memory is susceptible to this, and it can cause parts of the drive to become corrupt." Ejecting a drive does NOT power off the USB port. You are always abruptly removing the power. Reasonable drives are all going to have local power management that will allow them to operate for a short amount of time following disconnection. As for the head crashing on a disk drive powered off, the same applies. Modern drives auto-park the heads as part of their power-down sequence. Your statement may have applied 20-30 years ago.

  5. Derek
    March 27, 2015 at 12:35 pm

    I disagree after losing important data on top USB flash drives for removing without ejecting [no settings changed] I invested in zentimo which assist you force write cache closure.

  6. widgetsdaddy
    March 27, 2015 at 11:18 am

    I once accidentally nudged a drive that stayed attached to the computer but disconnected internally. The drive contained thousands of photographs that I'd been working on and were filed in a rather complex series of folders. The drive became corrupted and I had to use recovery software which discovered most, but not all, photographs. The filing system was destroyed. I loaded the recovered files onto a hard drive but I couldn't access the photos for more than a few seconds each without the drive freezing for a short time. Each photo had to be individually categorized and sorted into a new filing system - it took me months.

  7. Neil Hobbs
    March 27, 2015 at 7:17 am

    Interesting article. I have never ejected drive on windows & never had any issues. I have been using correct procedure in my car though

    • caswell
      February 18, 2016 at 12:53 pm

      for me this is specific to mac. i have 2 different brand laptops with different versions of windows and one macbook. the mac gets upset when i pull out a flash drive without warning it. i wanted to say abruptly pull out, but since i was used to all other brands of computers not giving a shit prior to my mac, i like to think abrupt is the wrong word considering that i feel a warning to my computer is uneeded. anyway, i remove several usb flash drives from my mac several times a day since i put the usb into my tv to watch the programs. i've never lost anything by not ejecting the drive. basically, i feel like apple is being a whiney bastard and should shut up, so i openly accept the nasty message that follows. this post solves nothing and is just a peek into the plethora of annoying shit that annoys me. apple could easily program the computer to dissolve the majority of remaining electricity when the drive is not in use. apple loves bossing us around with their software though so it's no surprise. in conclusion, pulling your drive out manually only requires you to click one spot post ejection, manually warning the computer pre ejection is a few clicks. one could argue i've clicked hundreds more times writing this than one would spend doing the prior over a long period of time. oh well, this is where my morals lie i guess. first world problems?

  8. Nahla
    March 27, 2015 at 6:28 am

    I always eject drives properly. However, you mentioned that MTP doesn't need to be ejected; true, but I had already experienced losing some data--twice--because of it. I'm not sure why, but I remember I lost some important big folders in my Android after using MTP. Or maybe because that time I kept switching between MTP and USB mode. MTP can be horribly slow and restricted (like I can't copy my backup apps unless they're compressed in zip files).

  9. xnor
    March 26, 2015 at 10:35 pm

    Using windows 7, i pulled a usb drive from the connector without first ejecting the drive. i was never able to access the usb drive again with any computer. luckly i was just transferring some files.

    • Eva
      March 26, 2015 at 11:47 pm

      That happened to me as well after transferring some pictures from my Smart(ass)phone to an external flash memory device using an OTG cable. I didn't eject, and my entire camera folder on the phones extSDCard became corrupted, and I couldn't write to it any longer.

      I ended up having to reformat the card and copy stuff back to it. Now I ALWAYS eject no matter what. If I cannot eject, I turn the phone off, and only then do I remove the flash memory stick.

  10. redhed17
    March 26, 2015 at 10:25 pm

    5 or so years ago I was copying data from multiple computers one after the other, and just pulled the USB pendrive out once the data copied, and going to the next computer. When I got home none of the data was on the pendrive. I had to go back the next day to copy the data again, so I always eject now. ;-)

    I also occasionally get the message that I can't eject a device because it is in use, but I can't find anything that is running.

    I use Windows btw. (currently Win 7)

  11. Adrian
    March 25, 2015 at 7:26 pm

    In Windows, a drive will intermettently a drive will NOT eject...it's always in use by some program which I can never find. Even third party programs like Unlocker and the lot don't work in some cases and at those times I must shut down the computer to safely remove the drive.

    I admit at those frustrating times I just yank it out and I've never had a crash yet. But yeah, that's not recommended.

  12. Gavin
    March 25, 2015 at 7:09 am

    How does this work when it comes to TVs and other player devices that have a USB port? I assume it's fine to just pull the drive out as the drive is only be read (the TV etc doesn't write to the drive). Can anyone confirm this?

    • Nando
      March 25, 2015 at 10:20 am

      +1 Was thinking the same thing. But from what i remember our LG and Samsung did have an eject button somewhere. Just always unplugged it when the TV was off.

  13. YB
    March 25, 2015 at 1:15 am

    This is and obviously will always be the proper way of ejecting a USB drive. I once made the mistake of just pulling out my USB HDD because I was in a rush after copying over some music, and boy was I sorry. The files I copied over was corrupt. They did not officially write to the partition on my HDD.

  14. likefunbutnot
    March 25, 2015 at 12:29 am

    I've seen data corruption happen on Windows. It's usually the result of pulling out a drive while files are specifically open and in use from that drive, but it's rare for people who understand how files work to have a problem. My Mac users have probably had more problems, but that's probably the result of being used to the Windows behavior than anything else.

    Drives on *nix have always needed to be mounted and unmounted, but I do feel that the Windows behavior for Flash drives is probably a better idea, if only for the overall health of the filesystem.

  15. Mike F
    March 24, 2015 at 11:28 pm

    This is one of the only good posts in a while! Can we get back to your roots and do more interesting informative posts like this one? I have only stuck around for the giveaways as I have noticed the articles moving more toward empty lists with catchy titles, and less and less useful for me. I don't mean to complain, I just wanted to make a positive vote for more like this! Thanks.

    • Alex
      March 27, 2015 at 3:13 pm

      Seconded

    • Rolfhu
      March 29, 2015 at 5:57 am

      Agreed

  16. Doc
    March 24, 2015 at 8:22 pm

    He didn't.

    "Ejecting a Drive on a Mac

    "All this information applies to flash drives plugged into Mac computers, and to Linux machines as well."

  17. George Monroe
    March 24, 2015 at 7:46 pm

    Why did you leave out Linux?

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