How To Format Your External Hard Drive or USB Flash Drive for Mac OS To Run iPhoto, Aperture or Time Machine

If you’re a Mac user using an external hard drive or USB flash drive to store files from iPhoto, Aperture or Time Machine, I highly recommend you format your hard drive to the Max OS Extended file system before using it.  This will give you better performance when using these applications and avoid potential data loss.

So What’s Wrong With My Current File Format?

Most external hard drives are formatted to the FAT32 file system by the manufacturer. This is a Windows file format.  Manufacturers use it because it’s compatible with Mac operating systems.  But it has limitations…

FAT32 isn’t the most efficient file format for use with a Mac or Windows, for that matter, but it can be useful if you regularly need to store and access small files and move them between a Mac and a Windows machine. [another tutorial – how to format my external drive to work on both Mac and Windows computers]

The FAT32 file format has 3 main limitations when used with Mac OS.

  1. You cannot save a file to a FAT32 formatted drive if the file is larger than 4GB in size.  (This can be a huge limitation if you work with video files or large backups).
  2. Apple’s Time Machine backup utility is unable to store data on the FAT32 formatted hard drives.
  3. FAT32 file systems are much slower in terms of performance than other file systems.

Some Known Problems using FAT32 Formatted Hard Drives with Mac OS Apps

iPhoto: Saving or backing up your iPhoto library to a FAT32 formatted external drive may result in poor performance or data loss.

Aperture: This popular photo editing software by Apple is unable to use FAT32 formatted drives to create photo libraries or vaults.

Time Machine: To use your external hard drive to backup your Mac, you’ll need to change the hard drive format to the Mac OS Extended format.

Formatting Is Straight Forward and Free

The process of formatting an external hard drive essentially involves erasing all the data and setting up the file format you want to use for the drive. It’s a straight forward process and Mac computers ship with a handy little utility to help you do this, so you don’t need to buy any software to format your external drives.

How To Check Your Hard Drives Current File Format

Not sure which file format your external drive is currently using, well let’s find out.

Open a Finder window and (1) right mouse click the name of the external drive you want to check and then (2) left mouse click “Get Info” from the context menu.

How to check your external hard drives file format

In the window that appears, under the General section you’ll see the current Format of your external hard. If it’s formatted to the FAT32 file format, it will say “MS-DOS (FAT32)”.

Find Your Hard Drives Current File System

Formatting For Better Performance and Compatibility with Mac OS

Now if you’re a Mac user, like me, you’ll only want to use your external hard drive or USB flash drive with a Mac operating system then go ahead and follow this tutorial and let’s get that external drive formatted so that it gives you better performance (works faster) and improved compatibility.

WARNING: If you have already been using your external drive, please backup your data as formatting a hard drive will erase everything (all data and disk partitions).

I suggest making a temporarily copy of all your files to another hard drive such as your Mac computers desktop before formatting it.  You can copy the files back to the external drive once it has been correctly formatted.

For this tutorial, I’m formatting a SanDisk Ultra 32 GB USB flash drive that I have purchased recently for under £10 from Amazon.  I have already saved some files on it but I didn’t format it to Mac’s preferred filesystem, so I’m going to do that right now.

Ok, let’s do this…

How To Format a New External Hard Drive or USB Flash Drive for Mac OS.

1. Insert the external drive or USB flash drive into a free USB slot on your Mac.

2. Back up any data on the drive. (I copied all the files and folder from my USB flash drive to a newly created folder on my computer’s Desktop called “temp files”.)

3. Launch Disk Utility. You’ll find this in the Applications folder, then Utilities. A quick method, that I like to use, is to open Spotlight (press CMD + SPACE). Start typing Disk Utility and when you see the Disk Utility app, press Enter to open it.

How To Launch Disk Utility on Mac

4. Find the name of the external hard drive you want to format from the left hand column of Disk utility and click it. Mine’s called SanDisk Ultra Media.

Find the Name of Your Hard Drive in Disk Utility

5. Click the Erase tab from the top of the Disk Utility window.

Erase Button in Disk Utility

6. In the next window, you can rename your external drive (optional), choose a Format and a Scheme. For the name, pick anything you like but stick to only letters and numbers (no special characters or symbols). For Format choose Mac OS Extended (Journaled). For Scheme choose GUID Partition Map.

Before (you’re may look different, depending on your hard drives current file format and scheme):

Rename Your External Drive and Choose File Format and Scheme


After Renaming External Hard Drive and Choosing File Format and Scheme

7. Next, if you have any data or files on your external drive and you feel they need to be erased a little more securely, then click Security Options and choose a setting from Fastest to Most Secure.

Please Note: Increasing the security level will make the formatting process take longer. Personally for me, fastest option is secure enough for most of the data and files I keep on an external drive.

Choose Your Security Options in Disk Utility
8. Click Erase.

9. Once the drive has been formatted, simply click Done. You’ll notice the name of the external hard drive has also been updated in the left column.

Your External Hard Drive Has Been Formatted

Your external hard drive is now ready to use and fully compatible with your Mac OS X. Go ahead and close the Disk Utility window and open finder to locate your newly formatted USB drive.

You can check that the drives filesystem by right-mouse clicking the drive in Finder and left-mouse clicking “Get Info”.

Please remember that the time it takes to format your external drive will depend on the size of the drive and also the security options you chose during the process.

Do I Really Need To Format My External Hard Drive?

If you’re external hard drive or USB drive is working slowly or having problems, or you want to use it for your Time Machine backup’s, to create a bootable Mac OS X volume, to save Aperture or iPhoto files or large video files or to just generally use it solely with your Mac, then format your drive to the Mac OS Extended file system using the process above for full compatibility and better performance, it only takes a few minutes and will save you time and frustration in the long run.

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