How to change the letter assigned to a drive – and why

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Every drive on your Windows computer has a letter of the alphabet assigned to it. The hard drive is probably drive C, and the CD/DVD drive (if you have one) is probably drive D. If you plug in a flash drive, it would most likely be drive E, since a new drive will take the next available drive letter. But if you set up a regular backup to a portable USB drive, you need to change the drive letter of that drive first. Here’s why.

change drive letter


When you set up a backup that goes to a portable or external hard drive, you have to tell the backup software a few things.

  • What files and folders to back up
  • How often to back up
  • What time of day to back up
  • Where to send the files and folders for the backup

That last item – where to send the backed-up files and folders – is the key element here.

So you have your external drive plugged in, and let’s say it takes the drive letter “E” since that is the next letter available, alphabetically. This means that each day, your backup program will┬átake those selected files and folders and put them in their proper place on drive E, your backup drive.

And that’s all fine, until something different happens.

When you’re using the computer, you should not have the external drive connected to it. But let’s say you are using the computer, and for whatever reason, you plug in a flash drive to see what’s on it. Then you leave that flash drive sitting in the USB port. That means the flash drive is now drive “E”.

Later on, you plug in your external drive so that the computer can do its backup. Maybe the backup is set to happen at 1 am (a popular time for overnight backups to start). BUT – what you didn’t notice is that the external hard drive is now drive “F” – the next available letter in the alphabet.

So when your backup program fires up at 1 am, it’s going to look for drive “E” – just like it’s supposed to – but drive “E” is the flash drive. There are several problems that could arise from this:

  • the flash drive probably doesn’t have enough available space to do the backup
  • the flash drive might not have the folder the backup program would be looking for to store the backup
  • if you forget the flash drive is there, you might think everything is fine and not realize for several days or even weeks that you haven’t been doing a backup

All of those problems can be avoided if you just do one thing when you’re setting up the backup. This is something I do every time I set up a backup for a client. You should change the drive letter for the external/portable drive, and you should assign it a letter that’s way up in the alphabet, like “P” or “M”. That way, it will always stay that letter when you plug it into your computer. The only way you could “bump” that external drive off of one of those letters would be to plug in so many other flash drives or other things that all the other letters are used up. That won’t happen, so you’re safe with a letter that is near the end of the alphabet.

Here’s how you change the drive letter:

  1. Plug in your portable drive
  2. Click the Start button, and RIGHT click on either “Computer” (Windows 7 or 8) or “This PC” (Windows 10)
  3. In the little menu that comes up, click on “Manage”

change drive letter

4. In the new window that opens, click on “Disk Management”

change drive letter

5. Now you’ll see a list of all your drives, including the external drive

change drive letter


6. Do a RIGHT click on the external drive and choose “Change Drive Letter and Paths”

change drive letter


7. Now click the Change button:

change drive letter


8. Click the drop-down menu and choose the letter you want to use, and click OK:

change drive letter


You might get an alert that pops up saying that some programs may not work properly if you change the drive letter for this drive. That’s fine, because the only program that will use this external drive is your backup program (I use Macrium Reflect), and you’re going to tell it the new drive letter anyway.

Remember, you need to do this BEFORE you set up the backup. Otherwise, you’ll have to go back into the backup program and tell it the new drive letter too.

And as always, if you want to set up a backup and this all sounds like more than you want to deal with, I can do all of this for you remotely. So you don’t have to bother with it, you don’t have to bring your computer anywhere, and you don’t have to have someone come in to your home or business.

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