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Why Does My USB Drive Say It’s Full When It’s Not?

Mac book with code on the screen.

USB flash devices are normally very reliable devices, but they can occasionally have problems. Sometimes it’s an issue with the USB ports not working; other times it’s because the computer doesn’t recognize the USB. One of the most common issues (and the easiest one to fix) is when your USB drive reads as full when it still has room on it!

Don’t despair if this happens. It can be confusing to have a drive that you thought was empty turn out to be “full”, but there’s a good reason why this can happen. Best of all: it’s an easy problem to solve! Read on as we explain why even the emptiest of USB drives can get filled up.

Three Hidden Files

Just because your flash drive is brand-new doesn’t mean that it’s empty. It’s a very common misconception about USB drives. The truth of the matter is that no flash drive is 100% empty when you purchase it. A “blank” drive still contains three hidden folders on it. These folders are:

  • .fseventsd

  • .Spotlight-V100

  • .Trashes

These three hidden folders are part of the initial formatting of the drive. There are four different types of formatting for data drives:

  • NTFS

  • FAT

  • FAT32

  • exFAT

All standard flash drives that are smaller than 32GB are formatted with FAT or FAT32. These will be the most common types of formatting you’ll encounter, but it’s possible you may be using an NTFS or exFAT drive. If so, don’t worry: everything we’re going to tell you in this article applies to those formats too.

These three folders are placed on the empty drive to help your computer communicate with the flash drive. The “.Spotlight-V100” and “.fseventsd” folders contain meta data (i.e. data about data) that helps with the indexing of the files on your flash drive. They are not the reason why your USB drive is being read as full when it’s not. The culprit that’s to blame is the “.Trashes” folder.

Take Out The Trash

When it comes to taking out the trash, flash drives are a lot like computers: Deleting something doesn’t automatically make it go away. This is the number one reason why USB drives read as full- It’s because your flash memory is being used up by your deleted data!

When you delete a file on a hard drive, it gets sent to a waiting area where it can either be restored or permanently deleted. Flash drives work the same way: that’s what the “.Trashes” hidden folder is for. There is one crucial difference, however, between how hard drives and flash drives take out the trash: there’s no “empty trash” function inside your USB.

The only way to free up that used up storage space is to permanently delete your trashed files. To do that, though, you’re going to need a little help from your home computer.


Hook It Up

You can see the deleted files on your flash drive by plugging your flash drive into a computer.  Before you do that, though, go onto your computer and empty out the trash bin. You don’t want to confuse which files are from your computer and which are from the flash drive, after all.

You can see the full contents of your USB’s trash directory inside the computer’s trash bin. It’s only here, inside the computer’s trash, that you can fully delete your trashed flash drive files.


The only downside to all this: Doing this won’t TOTALLY clear out your drive, either. Fragments of data can get left behind in your flash drive, even after you’ve cleared the files out via a computer’s trash bin. These fragments of data are tiny and normally shouldn’t be a problem, but they can build up overtime and reduce your drive’s storage capacity. The only way to delete these stowaway pieces of data is to completely reformat your USB drive.

The most important thing to remember about reformatting: It will COMPLETELY erase your flash drive. Any data on the flash drive will be lost and irretrievable. Make sure that you’ve backed up your data on your USB drive before reformatting it.

To reformat your drive on a Windows computer, go to “Computer”. This is the part of the menu that will lead you to your hard drive and other removable drives. Select your flash drive by right clicking it. A “Format” option should appear in the window. Click on that and the drive will be wiped clean. You’ll know you’ve done it right because your computer will put up a warning message to make sure that you know what you’re doing before proceeding with the reformatting.


If you’re on a Mac computer, you’ll select “Disk Utility” instead. You should find your flash drive listed on the left. Select it and then click the second button on the right that’s marked “Erase”. You can select how you want it formatted, rename the drive, and a few other options. Click erase and it will empty out your flash drive.


In Conclusion

If your USB drive says it’s full when it’s not, it’s because you still have trashed files on the drive. It’s an easy problem to fix: a quick trip to the trash bin should do the trick. Failing that, reformatting will restore the drive to its pristine “empty” state.

If you have questions about your USB drives, Premium has got the answers. Send us a message and we’d love to get back to you.