How to clean up a Thumb Drive

How to clean up a Thumb Drive
Mac Tip #350, 06 August 2008

Emtec 1Gb Thumb Drive

Emtec 1Gb Thumb Drive

Many people use thumb drives — those tiny ‘sticks’ you plug into a USB port — for storing backups of important documents, and they’re great for that purpose: quick, easy, convenient. Copy files to the drive, drag files from the drive, add, delete — it all takes but a moment.

When things go wrong

The Finder shows several files on my No Name thumb drive

The Finder shows several files on my No Name thumb drive

Until, maybe, something goes wrong, as a friend found recently when one file claimed to be corrupted, and the daily backups wouldn’t complete. This problem isn’t unique to thumb drives, by the way — it can happen any time to any storage medium.

In the screenshot my No Name thumb drive has a bunch of files on it.

How to reformat a thumb drive

In my friend’s case we did some troubleshooting and then decided to reformat the thumb drive. Here’s how to do that.

Disk Utility displays a list of drives

Disk Utility displays a list of drives

Start up Disk Utility. You should find it in the Applications — Utilities folder. The Disk Utility window opens and displays a list of disks in the left-hand column.

Plug in the thumb drive you’d like to reformat. It should also show up in the list of drives.

In the screenshot you can see a list of the internal hard drive and DVD drive on my Mac. My No Name thumb drive is listed, and I’ve selected it in the list. Click on the thumbnail images in this post to see larger versions.

Warning: erasing destroys data

Warning about erasing a disk with Disk Utility

Warning about erasing a disk with Disk Utility

Click on the thumb drive in the list to select it.

Now take great care in the next step. When you reformat a drive it completely erases everything that’s on it.

Make sure you select the correct disk and also make sure you have copies of any files on the thumb drive that you wish to keep.

After selecting the thumb drive in the list click on the Erase tab on the right hand side of the window.

Choose a Volume Format from the pop-up — try Mac OS extended (Journaled), and if you wish, give the thumb drive disk a name.

Double check that you will be erasing the correct disk and then click the Erase… button. An alert appears reminding you that all data will be erased and asking you to confirm that you wish to erase the drive. Click Erase to wipe everything or Cancel to abandon what you’re doing.

My screenshot shows that I’ve selected a thumb drive called 964 MB Ut165 USB2FlashStorage Media and am about to click the Erase button on the alert.

My Thumb Drive now has a name

My Thumb Drive now has a name

After a few moments the disk is wiped clean. When I look at the disk in the Finder I see that no files remain. In my screenshot you can see the thumb drive now shows up in the left-hand column of Disk utility with the name I assigned it.

Security Options…

Secure Erase Options in Disk Utility

Secure Erase Options in Disk Utility

If you wish, click the Security Options… button before you erase the thumb drive. Choose from the different methods for erasing, depending on your purpose.

If all you want to do is wipe a drive you’ve been using so you can start fresh choose Don’t Erase Data, or Zero Out Data.

If you’re cleaning up a drive someone else gave you, to be sure there’s nothing nasty on it, or to give the drive to someone else, choose a more secure option such as 7-Pass or 5-Pass Erase. The more secure the option you choose the longer it will take to erase the drive.

By the way: if you want to reformat a memory card to be used in a cellphone or camera first check the manual and help files for that device. You may be best to reformat the card in the camera or cellphone itself so it uses the correct formatting options.

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  1. Michael Yates said:

    How do i clean the connections on my thumbdrive.

  2. blra said:

    Thank you ! I just wanted to erase everything because for some reason some files did not want to get deleted (an unexpected error occurred)…

  3. Margie said:

    Erased one thumbdrive successfully, thanks. Can’t do the next one…says “couldn’t unmount disk”. What do I do???

    • Margie said:

      Just read someone’s comment above, and your answer. I closed everything, and now it erased. Thank you.

  4. Christina said:

    I am doing this action right now on a thumb drive I bought last night to format it after I tried putting some pics on it and not being able to find it, AND it’s been going for the last 15 minutes! HELP!!!!!!

  5. CS said:

    Thank you this saved me for next period!

  6. Brian said:

    The info was very helpful. I DO hate that clearing the memory from my flash is a 2-step process. Deleting From Drive, then Emptying the Entire Computer’s Trash. PLUS, when using a friends computer, I’m not comfortable deleting their trash (I’ll use the disk utility I guess.)

    Still, there really isn’t a simple 1 step permanent deleting contents from flash drive? Not a fan of the current set up.

  7. Michele said:

    Thank you! This was VERY helpful, and took only a few seconds, not only to understand it (very clear!) but also to execute.

  8. Stacie said:

    Beautiful! Thanks! My 4G thumb drive is 4G again. <3

  9. Denny Slaton said:

    This was easy to follow, but did not work. I got the following error message–
    Volume Erase failed with the error:
    Could not unmount disk

    Any thoughts on what to do next?

    • Miraz Jordan said:

      Denny, is it possible something on the thumb drive is still in use? Did you open a photo or a document directly from the thumb drive, for example? If you did, and then closed the file but didn’t quit the app, that could cause a problem.

      What happens if you try to simply eject the thumb drive? Do you get a message that a file is in use?

      Try quitting all apps and then try to erase.

    • deb said:

      I had the same error message. Try switching to mac OS extended on (not journaled). That did the trick for me. THANKS for the GREAT tip!

  10. Peter said:

    was having problems clearing an old windows based thumb drive for use on my Mac.. this fixed everything.. thank you for posting this!

  11. Space Dragon said:

    this was really helpful! thanks for the good post

  12. Miraz Jordan said:

    Hi Jay,

    I just LOVE hearing that the MacTips have been useful. I’m so glad this one was able to really make a difference for you!

    Good luck with the project.



    • GaryF said:

      Hi Miraz
      I reformatted a thumb drive in disk utility so the kids could put MP3 files on it to play in the car. The first format I used MAC OS Extended – the player wouldn’t recognise the files. I tried again using MS-DOS (FAT) format, same deal, the files weren’t recognised and the player reads unsupported device. Can you tell me what I’m doing wrong?

      • Miraz Jordan said:

        Try reformatting it in the player, or check the player’s manual to find out what format it requires.

        • David said:

          The problem may be the partition map scheme. Disk Utility is probably using GUID by default. Your device is probably expecting Master Boot Record.

          Click on the disk (not the volume) in the left pane
          Click the Partition tab in the right pane
          Select 1 Partition layout
          Click Options underneath the Partition Layout box
          Select Master Boot Record and click OK
          Select MS-DOS (FAT) format
          Click Apply

  13. Jay said:

    This post totally just saved my butt from a big fat ‘F’ in my design class. My thumbdrive was ‘full’ even though I had deleted everything, which meant I couldn’t transfer my huge photoshop project to class. Three quick clicks after reading this post and I was back in business. THANK YOU!

  14. carolina said:

    oh wow!!! thank you sooo much! ive been trying to do this forever and i couldnt! you just saved my life!!!

  15. Lys said:

    THANK YOU!! Whenever I connected my thumbdrive to my photo printer it kept finding 320 photos (that weren’t ever visible to me but that I used to have stored on the drive) and now they’re GONE!!

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  17. Miraz Jordan said:

    CL, Neena, Gina: thanks for the feedback guys. It’s so good to know the Tip has been useful.

  18. Gina said:

    Thank you so much for this. I still have no idea what files were stuck on my brand new drive, but this got them off after fiddling with it for WAY too long.

  19. CL said:

    Thank you. It worked perfectly. This problem has been bugging me for months. THANKS!!!

  20. Bubbowrap said:

    Miraz, I love you. I’ve been erasing the whole drive because of that problem, often being forced to redrag things into the thumbdrive once I’ve finished deleting what I didn’t want anymore.

    Thank you!

  21. Miraz Jordan said:

    When you delete the files do you just put them in the Trash? If you don’t *empty* the Trash then the files are still on the drive using up space.

  22. Dude said:

    I hate Macs. So bloody difficult to clean up/delete files from my thumb drive. For some reason, when I delete stuff it actually uses up space on the drive!

    • Stacie said:

      That is because you didn’t fully delete. If you use Disk Utility as the post explains, the thumb drive will be removed of all its data remnant. It is very easy. Takes thirty seconds. Which is the same amount of time it takes to delete large files from a thumb drive into the waste basket…

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