External Hard Drive For Mac and PC with Data Interchangeable

By Simon Irons / August 2, 2018
External Hard Drive for Mac and PC Interchangeable

Would you like an external hard drive where you can put music or photos so both the Mac and the PC can interchange files or listen to the same MP3s?

or your household has a few Macs and PCs that are in use for various things and you'd like a central external hard drive that you can use to pop files onto.

The Good News!

​The good news is that pretty much any external hard drive that can be physically connected to both your Mac and your PC can be changed so that both systems can read and write to it.

Or a portion of that external drive made shareable - interchangeable.

With a little know how.

 If you are thinking of an external hard drive to share between a Mac and a PC take a look at the ones I consider the best.

The Beauty of ExFAT

​Apple bought the rights from Microsoft to be able to format and read ExFAT file systems and a Mac can read and write to an ExFAT formatted hard drive.

A Windows PC can also read and write to an ExFAT formatted hard drive.

Hurray! ExFAT is the one common factor. Both Mac's and PC's can read from and write to ExFAT file systems.

What can be Shared?

​Files, documents, music, photos pretty much all your user data.

What cannot be Shared?

​Applications and Program files that are also known as executables.

Applications designed for a Windows PC must run on a Windows PC, in the same way an application that is designed for a Mac must run on a Mac.

Although those program files can be stored on a shared hard drive they must be run by the machine they were designed for.

Why Does it seem so hard?

Data Interchangeable Why Is It So Hard?

Well the thing is, it's not,

As long as you understand a few fundamentals.

Why Macs and PCs can't share an External Hard drive by Default

​Windows PCs

Are generally set up to use and understand NTFS (New Technology File System) as their file system.

​What is a file system?

​It is the structure the computer expects to see and read to find its operating system, your documents, photos, mp3s - in fact anything you've saved.

​​NTFS has been around since Windows NT back in 1993 and has been the default file system for Windows based computers since then. Of course it has gone through a few iterations and upgrades since that time.

NTFS was preceded by FAT32 an MSDOS based file system and due to backwards compatibility Windows PC's can read and write disks formatted with FAT32.

The ExFAT file system was introduced in 2005 for Windows NT and XP systems to get over some the file restrictions of FAT32. For example the maximum file size on FAT32 is 4GB. ExFAT is a better performing file system and can handle 16 Exibyte file sizes. Which is enough for most of us.

Now that we've taken that little history tour and you understand what a modern Windows PC is expecting of its file systems let's take a quick look at the Mac.

Macs

Are set up to use Mac OS Extended (Journaled) file system by default. This file system is also known as HFS+ (HFS plus).

​​Note that:

​​The latest Mac operating system High Sierra introduced a new file system called APFS (Apple File System) which is faster and more secure than Mac OS Extended (Journaled) file system. APFS is set up by default on Mac's upgrading to High Sierra with Flash drives or SSD drives.

A Mac can read files on NTFS and see a NTFS formatted external hard drive but cannot write to it.

So there you have it.
Your Mac can read but can't write to NTFS and your Windows PC cannot see, read or write to Mac OS Extended (Journaled) file systems or HFS+ or for that matter the new Apple File System.

The Middle Ground

​Now you have an appreciation of the different file systems Macs and PCs are expecting to see, you can understand why interchanging files needs thinking about.

Luckily there is a middle ground and that middle ground is an ExFAT file system.

How can an External Drive be Made Compatible and Shared?

​Formatted in ExFAT, a whole External Hard Drive can be shared between a Mac and a Windows PC and you can interchange files.

Or

Parts of an External Hard Drive can be made shareable between a Mac and a PC. With certain areas dedicated for your Mac to use. This is also known as separating an External Hard Drive up into sections known as partitions.

An Example

Partition 1 - used by the Mac only is formatted to the file system the Mac knows and loves Mac OS Extended (Journaled) file system. The PC cannot see this part of the external drive and is not aware it is there.

Partition 2 - used by the Windows PC only, formatted to ExFAT.

Partition 3 - a shared part of the disk that is formatted to ExFAT and both your Mac can read and write and the Windows PC can read and write to this part of the hard drive. And

What can be written are the files that you want shared between them.

Partitions just like external hard drives can be given a name and it's probably a good idea that the name reflects the partitions purpose. e.g. call a shared partition, "shared" or something more exciting that reflects its use.

Now we can get to the meat of how you do this.

What is Needed Before you Start?

​a. An external hard drive attached to your Mac via USB.

USB 2.0, 3.0, 3.1 or USB C are the common external hard drive standards.

Buy an external hard drive that supports the physical connections and speed you need for both Mac and Windows.

USB 3.0 and 3.1 are physically different ports but are backwards compatible. You may need a cable adaptor if say your Mac has a USB-C port but the Windows PC you want to share with has a USB 3.0 port.

Not sure on the differences between USB ports have a look at my article on connecting up an external hard drive. There is an explanation in that article with pictures of the different USB standards.

I'm suggesting that you plug the external drive into your Mac to set up.

Firstly as only the Mac can format an external hard drive as Mac OS extended (Journaled) file system. And you are going to need to do that step first.

- well you can bypass that step and you may have no problems … but again you might.

And secondly, because the Mac is picky and at least that way you'll know its happy with the way the external drive is set up.

b. A large enough external hard drive to accommodate everything you want to put on it. Don't scrimp here, you'll regret it later.

c. The external hard drive formatted to Mac OS Extended (Journaled) file system. You can go a head without this step but to be honest I've seen Mac's get picky about formatting the drive to ExFAT without it formatted to Mac OS Extended first. It only takes a few minutes, I'll tell you how, so why worry about it.

It's pretty easy to do and within a few minutes you'll be up and running.

First I will cover the scenario where you want the complete drive interchangeable and compatible between the Mac and the PC.

​Note: If there are files

​​​already on the hard drive you will need to copy them off as formatting will erase the files.

​Whole External Hard Drive Compatible with Mac and PC

1. Power up and sign into your Mac

​​Connect the USB cable to your hard drive and plug the other end into your Mac. If the drive needs an external power supply, plug that in ahead of connecting up the USB cable.

2. Find the external hard drive icon on your desktop

​It will look similar to this.

External Drive Icon On Desktop

External Drive Icon On Desktop

If the picture hasn't appeared on the desktop and you're not sure what to do next take a look at my article "Connecting up an external hard drive on a Mac" - link to article

3. Open up Disk Utility

​You can find Disk Utility by either clicking on the Application folder, then clicking on the Utilities folder and double clicking on Disk Utility to start it up.

Disk Utility In Application Folder

Disk Utility In Application Folder

​or you can search for it using spotlight search. The icon for Spotlight search should be at the top of your desktop

Spotlight Search Symbol

Spotlight Search Symbol

​Type in Disk Utility.

Disk Utility In Spotlight Search

Disk Utility In Spotlight Search

Click on Disk Utility to start it up.

4. Select your external disk from the external disk section on the screen

Disk Utility Select External Hard Drive

Disk Utility Select External Hard Drive

Disk Utility will now give you information on that external hard drive.

5. Look at the options across the top of Disk Utility

​You'll see the option to Erase. This is how you set up the formatting of the external hard drive.

Disk Utility Erase Option

Disk Utility Erase Option

6. Click on Erase

​You will now have a screen where you'll be able to give the external hard drive a name and select the formatting - the file system you want.

Disk Utility Formatting Page

Disk Utility Formatting Page

If this is your first time through this process and the external hard drive isn't already formatted in Mac OS Extended (Journaled) file system, select that as your option and then click erase at the bottom right of that window. Wait a few minutes and your done. Then you can go through steps 1 - 5 above to get back to this stage.

​Select ExFAT

Selecting ExFAT in Disk Uitility

Selecting ExFAT in Disk Uitility

Once you have selected the ExFAT formatting you'll be able to click on the Erase button toward the bottom right of that screen and in a few minutes the hard drive will be formatted.

And you are done, the entire external hard drive is now capable of being read and written to by both Mac and PC.

You can drag and drop files, create folders as you wish.

And it only took a few minutes.

If this is all you want to do then you can go ahead and use the drive on your Mac but before unplugging the drive

read step 7 and Eject the external hard drive to properly disconnect the drive.

If you are now ready to create shareable partitions jump ahead to step 8.

7. Ejecting the External Hard Drive

If you just plugged out the USB cable from your Mac or your PC you risk corrupting the data on that drive. This is because both Mac OS and Windows will hold some data in its memory related to that hard drive and its files and that information will only get written down when you tell it to.

Ejecting your external hard drive tells Mac OS to write that data so you can safely remove the drive from the computer.

The equivalent is ejecting your external hard drive from a Windows PC so that it writes down all necessary data to the drive and then its safe to take out the USB cable.

To do this;

Hover over the Icon for the External Drive on the desktop. Right click and select the Eject option.

Right Click to Eject External Drive

Right Click to Eject External Drive

or Go to the finder window and click on the arrow to the right of the drive name to eject the drive.

Wait a few seconds for the icon to disappear.

Wait till the fan stops moving if your external drive has a fan or for the light on the hard drive to go off.

Then you're free to disconnect the USB cable.

Partition of the External Hard Drive So it is Interchangeable with Mac and PC

​You can create partitions when you want sections of your external hard drive that are set up for specific things.

8. Format the External Hard drive

​The first thing is to have the external hard drive formatted to Mac OS Extended (Journaled) file system.

Steps 1 - 6 above.

If the external drive is already formatted to Mac OS Extended (Journaled) file system, there is no reason to do it again. You are ready.

Staying within Disk Utility you can now go on to create the partitions on the external hard drive.

9. To Partition the Drive

​Across the top of the Disk Utility screen you'll see a button labeled 'Partition'.

Click on that.

Select Partition on Utility Screen

Select Partition on Utility Screen

​Now you'll see the entire external hard drive represented by a large circle.

First Partition Screen

First Partition Screen

Right now there is only one partition. The whole disk.

Toward the bottom of the partition screen is a + button.

Partition Plus Sign on Screen

Partition Plus Sign on Screen

You click on this button to increase the number of partitions you want. The minus button decreases the number of partitions.

For this example we'll have a scenario where there are three partitions.

  • One for Mac files only
  • One for Mac and PC to share
  • One for a Mac Time Machine backup

You click on the plus sign twice to create two partitions. You'll then have three in total. The one you started with and two more.

10. Choosing a file System for your Partition

​A partition to be used for Mac only is formatted as Mac OS Extended (Journaled) file system

A partition to be used for both Mac and Windows is formatted as an ExFAT file system.

A partition to be used for Mac Time Machine backup is formatted as Mac OS Extended (Journaled) file system

11. Select and Give each Partition a Name

​Select each partition in turn. Click on the partition - The segment of the disk you want to change.

Give the partition a name that will be useful so that you know its purpose.

Select the file system type.

​Set the size.

Create Partitions

Create Partitions

Click on the next partition segment and repeat.

Do this for each partition in turn and you'll see the size of each slice of the external hard drive change as you change its size.

12. Click Apply when you are Happy

​And that's it. Wait a few minutes for the Mac to do its work and you're all done.

The external hard drive is set up for Mac and PC and partitioned up as you want.

When you plug in the external hard drive to your Mac your Mac will see all the partitions, the Mac OS ones and the ExFAT one(s) - depending on how many you have created.

If your not sure how to use an external hard drive take a look at my article on how to connect an external hard drive and jump down to the section on how to use an external hard drive.

When you plug in the external hard drive to your Windows PC the PC will only see the ExFAT partition(s).

13. YouTube Video

​If you're still feeling in the dark about formatting and partitioning and would like some extra help watching this YouTube video will help.

Video Credit: Acquevara

Acquevara's YouTube video shows you how easy this is.

Other Frequently Asked Questions

What about Time Machine?

​​Time Machine backs up to and reads its backups from a Mac OS Extended (Journaled) file system NOT ExFAT.

So you can use the ExFAT drive or partition to share files between a Mac and a Windows PC but you can't use Time Machine to backup to an ExFAT drive or partition.

If you have created a Mac OS Extended (Journaled) file system partition for a Time Machine backup on your external hard drive then all you need to do it hook that partition up to Time Machine and you'll be good to go with your backups.

Take a look at my article on how to backup to an external hard drive and it's all in there. Within a few more minutes you'll be golden.

Final Words

​Well done, thanks for sticking with me till the end. We've been on quite a journey.

You should by now have an appreciation of what a Mac needs and what your Windows PC needs. How to create an external hard drive so its interchangeable between a Mac and a PC, either in whole or in part with a shared partition.

I trust this article has you happily swapping files back and forth.

If you'd like to choose a suitable external hard drive to share between a Mac and a PC take a look at the this selection..

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