Photo by Sharon Vaknin/CNET If you need to expand your storage space with an external hard drive and you use both Mac and PC, you'll likely run into a few obstacles. Hard drives advertised as being compatible with Windows and Mac OS may have misled you into thinking you could actually use one hard drive for both computers. You can, but not out of the box. Most external hard drives (HD) are sold in a format called NTFS, which is designed to work with Windows. Macs read and write to a different format, called HFS+. Another format, called FAT32 is compatible with both OS platforms.
Here's a look at how the different HD format types function: FAT32 (File Allocation Table) - Natively read/write FAT32 on Windows and Mac OS X. Maximum file size: 4GB - Maximum volume size: 2TB NTFS (Windows NT File System) - Natively read/write NTFS on Windows.
Apr 22, 2012 - Launch Disk Utility, found within /Applications/Utilities/ Connect the drive you wish to format for dual compatibility to the Mac. Click the drive name on the left side list in Disk Utility, and then click the “Erase” tab. Click the pulldown menu alongside “Format” and select “MS-DOS (FAT)”. Yes, connecting an external hard drive or USB flash key to a Mac will generally read and work fine as is because the Mac can easily read other filesystem formats, including Windows MSDOS, FAT, FAT32, ExFat, and NTFS formats, but unless you intend on using the drive between a Windows and Mac machine, formatting it to be entirely Mac compatible.
Read-only NTFS on Mac OS X - Native NTFS support can be enabled in Snow Leopard and above but has proven instable. Maximum file size: 16 TB - Maximum volume size: 256TB HFS+ (Hierarchical File System, aka Mac OS Extended) - Natively read/write HFS+ on Mac OS X - Required for Time Machine - Maximum file size: 8 - Maximum volume size: 8EiB Isn't FAT32 the obvious solution? According to the list above, formatting your hard drive to FAT32 so that you can read and write on either OS seems like the obvious solution. The video and directions below will guide you through the process, but before you format your HD to FAT32, beware of these drawbacks.
FAT32 offers no security, unlike NTFS, which allows you to set permissions. If your HD gets into the wrong hands, that person will be able to access your data. The max size for any given file stored on a FAT32-formatted HD is 4GB.
So, for example, if you want to store a 9GB movie, it will be impossible. In general, FAT32 drives are more susceptible to disk errors. It's not a huge issue, but FAT32 is less efficient at storing files. Its large cluster sizes waste disk space, unlike the other HD storage formats. 2:55 If you've considered these issues and would still like to use FAT32, this video will guide you through the process of formatting your HD to FAT32 using a Windows or Mac PC: OK, what are my alternatives to using FAT32?
The good news is, it's not FAT32 or nothing. The alternative solutions do require more tinkering, but if you do not want to risk FAT32's lack of security, choose from one of the following alternatives. Option 1: Format to NTFS, and use NTFS-3G to read/write on Mac. If you keep your hard drive's out-of-the-box NTFS format for all the reasons FAT32 displeases, there's a workaround that will allow your Mac to read and write files to the drive. Is an open-source program that, when coupled with, will let you use your NTFS drive on your Mac.
However, it is an open-source program, so use it at your own risk. Many have vouched for its success, but others complain about bugs. The commercial solution, which will give you access to support and software updates, is. It's $20, offers Lion support, and you get a five-day trial to try before you buy. Option 2: Format to HFS+, and use HFS Explorer to read/write on PC. Conversely, you can format the HD to HFS+ and use HFSExplorer for Windows to read and write to the Mac-formatted hard drive. To get started, you'll first have to format the hard drive from NTFS to HFS+.
Here's how: Plug your HD into the Mac and open Disk Utility, which can be accessed by searching for it in Spotlight. Then, select your hard drive from the left sidebar. Now go to the Erase tab. In the Volume Format list, select Mac OS Extended (Journaled). Then, click Erase at the bottom to format the drive. Please note that this will complete erase the drive. Any data you want to keep on that drive must be backed up elsewhere first.
Now that the hard drive is formatted to HFS+, on your Windows machine to get read and write access to the drive. This is an open-source program, so use it at your own risk. Alternatively, you can opt for paid software like instead.
Option 3: Create two partitions on your hard drive to use with each OS, separately. This solution is a little different than the previous two because instead of having one hard drive that works with both machines, you're splitting your HD into two sections, each dedicated to a different OS. For example, if you have a 1TB hard drive, 500GB of storage can be used with your Windows computer, and 500 will be dedicated to your Mac computer. You won't be able to write to the Mac side from your Windows computer, and vice versa, but it's a good solution for people who want all the advantages each format has to offer for its respective system.
Here's how to do it: Step 1: Connect the empty external HD to your Mac and launch Disk Utility. Select the drive from the left sidebar, then click the Partition tab.
Under Partition layout, select '2 Partitions.' Now, drag the boxes to adjust the size of each partition. For example, you might want more storage for your Mac than you do for your PC.
Now, click on the top partition, name it 'Windows,' and change its format to MS-DOS. Then click the second partition, name it 'Mac,' and change its format to Mac OS Extended (Journaled). Give your settings a final lookover and click Apply. Step 2: Plug the hard drive into your Windows PC. Open the Start menu and search for Disk Management. Select the search result and the Disk Management utility will launch.
In the left sidebar, you should see your hard drive and its partitions. Right-click the Windows partition and select Format. In the Format dialog box, under File System, select FAT32. Click OK and complete the format process.
With these three options you'll be able to take advantage of either platform's offerings, be it Time Machine support or security options. In the end, you may end up using FAT32 for its simplicity, but don't say I didn't warn you about the risks.
If you're installing a new hard drive, or need to wipe your drive clean for that 'fresh' feeling, you'll end up formatting your drive. Formatting will check the drive for errors, and prepare it for use. If a drive has data on it, formatting the drive will remove all of the pointers to your files. Note: Formatting doesn’t securely erase the contents of a hard drive. With freely available and easy-to-use tools, anyone can successfully recover data from a formatted drive. See for information on wiping your hard drive clean. Formatting can take hours to complete, but it is a good option when you have a new or inherited drive that is not properly formatted, a drive overrun by malware or other software problems, or a drive in need of a fresh start before a Windows installation.
Traditional, magnetic-platter hard drives as well as solid-state drives can be formatted. Before you begin, be sure to on the disk before you format. Use Disk Management To partition and format your drive, you can use Windows' built-in tool called Disk Management.
You can repartition and format your hard drives in Windows using the Disk Management tool. In Windows 7, click Start. Next, right-click Computer, then click Manage. The 'Computer Management' window will open. In the left pane, click Disk Management (under Storage).
In Windows 8, right-click the Windows button, and select Disk Management. If your disk is not initialized (as is sometimes the case with brand-new drives), you’ll be prompted to initialize it. If your disk is 2TB or more in size, select GPT; otherwise, stick with MBR. A list of all connected disk drives is displayed in the center. Unpartitioned drives appear with solid black bars and the label 'Unallocated.'
Partitioned drives appear with solid blue bars and a drive letter. Partitioning your drive To format an internal or external hard drive to use for backup or additional storage, the drive needs to be partitioned. Partitioning divides your drive into sections, but you can choose to simply have one partition (a single section encompassing the entire drive). If your drive isn't partitioned, follow these instructions to partition it. Otherwise, skip down to the next section.
Right-click the black bar or the unallocated white space below it and select New Simple Volume Don't be dissuaded by the word, 'Volume.' It's just another term for 'partition'. Click Next. To create a single, whole-drive partition, make sure the 'Simple volume size in MB' value is the same as the 'Maximum disk space in MB' value.
Assign a drive letter of your choice. Select Format this volume. For File System, choose NTFS if you’ll be using the drive only with Windows machines.
If you will be sharing the information on the drive with Macs, choose exFAT. Keep Allocation unit size at Default. Choose a name for the partition under Volume label.
Do not select Perform a quick format or Enable file and folder compression. Confirm your selections and click Finish. Formatting your partitions Once your drive is partitioned, each partition will have to be formatted with a filesystem. Luckily, the Disk Management utility makes this really easy. Right-click the blue bar or the white space below it and select Format. Choose a name for the partition under 'Volume label.' For File System, choose NTFS if you’ll be using this drive only with Windows machines.
Linux machines can read unencrypted NTFS partitions as well. If you will be sharing the information on this drive with Macs, choose exFAT. Keep 'Allocation unit size' at Default.
Do not select Perform a quick format or Enable file and folder compression. Confirm your choices.
Formatting for a Fresh Windows Installation If you are formatting your primary hard drive with the intention of reinstalling Windows or restoring your PC to its factory-fresh state, you’ll need the restore disc(s) that came with your computer. If your computer manufacturer did not include restore media or you’ve misplaced it, contact the manufacturer directly for a replacement. You may also be able to create your own restore disc(s) or reinstall Windows from a factory-created partition on your hard drive; consult your computer’s documentation for details.
Insert your Windows installation disc or restore disc into your disc drive and restart your computer. For instructions on booting to your recovery partition, review your system documentation. If you are using a manufacturer’s factory restore disc or hard-drive recovery partition, follow the prompts to initiate the restoration process. Unless stated otherwise, your drive’s primary partition will be formatted and returned to its factory-fresh state. If you are using a Windows 7 installation disc, select your language, accept the Windows license terms, and select Custom (advanced) when prompted.
Select 'Drive options (advanced)' to format a drive from the Windows installer. Delete any partitions you want to remove by selecting them, clicking Drive options (advanced), and clicking Delete. Create new partitions by selecting unallocated space, clicking Drive options (advanced), and clicking New. Select Format after creating your partition(s).
After formatting is complete, click Next to start the Windows installation. Windows may prompt you to accept the creation of a small, system-reserved partition-accept it.