macOS exFAT | How to Fix exFAT Not Mounting on macOS Ventura/Monterey/Big Sur

exFAT on macOS: A Complete Guide

Mac users often opt for a compatible file system that syncs well with their Mac to quickly access files and data on external storage. exFAT is one such file system type that has a wide user base. But what is exFAT on a Mac? This article contains some relevant information about exFAT on macOS.

macOS exFAT refers to the support for the exFAT file system in the macOS operating system. exFAT, which stands for "Extended File Allocation Table," is a file system format primarily designed for compatibility between different operating systems and devices when dealing with large storage media. In macOS, exFAT enables users to read from and write to exFAT-formatted storage devices, such as USB drives or SD cards, that were prepared on other systems (like Windows). This allows macOS users to exchange data with users of different operating systems without the need to convert the file system.

To be more specific, exFAT, which was introduced with Windows CE 6.0 in the second half of 2006, is an embedded operating system for memory cards and flash drives. The entire File Allocation Table (FAT) family, including exFAT, is used for embedded systems because of its small size and suitability for low-memory and low-power solutions, as well as easy firmware implementation.

exFAT support in macOS

exFAT features file and cluster pre-allocation. This introduces the concept of "file pre-allocation," which allows you to define the size of a file before or during its writing process. This way, a file can be pre-allocated a large space, attempting to get a significant number of contiguous clusters in one allocation. As a result, the system can mark the file as contiguous, thus avoiding updates to the FAT chain.

It also employs a cluster bitmap to track allocated and free clusters, which significantly reduces the number or frequency of read/write operations required by the file system. Like other FAT file systems, its simple, streamlined structure and power-saving attributes make it well-suited for embedded storage solutions.

There are also specific features that make it particularly well suited to flash storage. One is aligned boundaries in the file-system structure, which allows the FAT offset and cluster heap to be adjusted at format time to minimize writes to blocks on the flash, thus preserving its integrity over the long term.

There is also an OEM parameter field that can be used to record the base storage block size and to log wear leveling, to maximize storage space and flash lifetime by minimizing writes.

All of these features are summarized in the table below.

macOS compatibility/support for exFAT

exFAT is compatible with all modern versions of macOS; that is, it's supported in Mac OS X 10.6.5 and later. For Windows users, exFAT is compatible with all versions of the operating system, such as Windows XP, Windows Server 2003 with update KB955704, Windows Embedded CE 6.0, Windows Server 2008, Windows 7, Windows 8, and Windows Server 2008 R2.

In addition to operating systems, exFAT is supported by various devices:

• Consumer electronics: cameras, camcorders, digital picture frames, mobile phones, personal computers, and the Internet. • Storage and media devices: USB flash drives, external hard drives, solid-state drives, SD cards, and next-generation media players (such as new flat-panel TVs, media centers, and portable media players).

Limitations of exFAT in macOS

One significant limitation of exFAT is that it lacks a journaling feature.

A journaling system is one that tracks and records changes to files on a disk in a log or journal before or as those changes occur.

Logging works by preallocating a specific area or log where changes are recorded. In other words, logging is useful because it allows for the recovery of corrupted data when damage occurs, using the log. The exFAT file system lacks this ability, making it more prone to errors caused by system failures, crashes, or power interruptions while running on a specific storage media. Interruptions can cause exFAT-based media to suffer from data corruption or loss.

Allocation Unit Size for exFAT in macOS

A cluster is the smallest unit of disk space that can be allocated to store a file. A single file can occupy one or more clusters, depending on the file size and the cluster size. Thus, if the actual size of a file exceeds the cluster size, it will occupy multiple clusters; if the actual size is less than the cluster size, it will still occupy at least one cluster. According to Microsoft, who created the exFAT file system, the standard cluster size for exFAT is:

• 7MB - 256MB: 4KB
• 256MB – 32GB: 32KB
• 32GB – 256TB: 128KB

Solving the Issue of exFAT Drives Not Mounting on macOS

Numerous online posts discuss issues with mounting exFAT drives on a Mac. Upon further investigation, you'll find that the exFAT drive not mounting problem can stem from various reasons. Here are some common causes:

• exFAT allocation unit size not supported on Mac.
• Damaged drive due to improper ejection, paused file transfers, and so on.
• Faulty USB cable or port.
• Software glitches.
• Damaged hard drive casing.

How can this be fixed? Here is a proposal.

• Fix 1: Manually Mount an exFAT Drive in Disk Utility
• Fix 2: Check Finder Preferences
• Fix 3: Use First Aid to Repair a Corrupted USB Format
• Fix 4: Mount an exFAT Drive on Mac Using Terminal

Solution 1: Manually Mount exFAT Drive in Disk Utility

Step 1: Open Disk Utility, and select the exFAT drive.

Step 2: Click the 'Load' button on the toolbar.

If it mounts your drive, congratulations! If nothing happens or you get an error, try one of the other solutions below.

Fix 2: Check Finder preferences

Your disk drive might not be showing up in the system settings. To resolve this issue, you can follow these steps:

Step 1: Open Finder.

Step 2: Go to Finder > Preferences.

This image shows the Finder Preferences window.

Step 3: Tap on “General.”

Step 4: Make sure “Hard Disk Drive” is selected.

Fix 3: Repair the corrupted USB using 'First Aid'

The first step will vary depending on your processor, but the steps are the same whether you're on Mac Big Sur, Mac Monterey, Mac Catalina, or any other version.

Step 1: Restart your Mac.

Using an Apple silicon processor: Press and hold the Power button until you see the Startup Options window. Click “Options” and then click “Continue.” Using an Intel processor: Press and hold Command + R until you see the Utilities window.

Step 2. Open Disk Utility, then click "Continue."

Step 3: Click on "View" and then "Show all devices".

Step 4: Select your drive and click "First Aid" and then "Run."

Solution 4: Mount exFAT Drive on Mac Using Terminal

Step 1: Launch Terminal from the Utilities folder within the Applications folder.

Step 2. In Terminal, paste the command diskutil list to see a list of all drives connected to your Mac.

Step 3. Find the identifier for your exFAT volume.

Step 4. Run the command: diskutil mountDisk /dev/identifier to mount your exFAT drive.

For example, if your exFAT drive is identified as disk2, the command would be diskutil mountDisk /dev/disk2.

exFAT on macOS

There are two ways to format a hard drive, one designed for advanced Mac users and the other for everyone else.

Use a disk utility to format it as exFAT.

If the file system on your disk is damaged, you might need to use exFAT instead.

Warning: All data on the hard drive will be erased! Back up your data first.

Step 1: Launch Disk Utility

Step 2: Select the drive you want to format.

Step 3: Click “Erase.”

Step 4: Name the drive and choose “exFAT” as the format. Click “Erase” again.

Your drive will be erased and reformatted. If you need to recover files later, you can use the Data Recovery Wizard for Mac, a powerful tool that can restore lost data due to formatting or damage with a 99.7% success rate.

Format to exFAT using terminal command in UTF-8 format.

Step 1. Plug the USB into your Mac.

Step 2. Press "Command + Space" and search for "Terminal." Alternatively, you can find the "Utilities" folder in Finder, then open Terminal from there.

Step 3. Enter diskutil list to list all available devices.

Step 4: Select the disk and run the command: diskutil eraseDisk exFAT MyDisk /dev/DISK_IDENTIFIER.

exFAT vs Mac OS Extended vs NTFS: A Full Comparison

Well, exFAT is just a file system, but there are others, like Mac OS Extended and NTFS. The big question is – what's the difference between these three? Let's find out.

exFAT and Mac OS Extended formats

Mac OS Extended, also known as HFS+ or HFS, is the default file system for all Macs that used a traditional spinning hard drive or a hybrid drive from 1998 up to the present. If your Mac is running macOS High Sierra and uses a hybrid or spinning hard drive, its default file system will still be Mac OS Extended. Just remember that you'll need to set an encryption key for both of these options, and encryption may slightly decrease performance.

Here are some recommendations on how to choose a file system and a comparison between exFAT and Mac OS Extended:

When formatting a USB drive or SD card, exFAT and FAT32 [MS-DOS (FAT)] are your best options. Choose exFAT for SD cards 64GB and larger, and MS-DOS (FAT) for 32GB and smaller.

When formatting an external hard drive, such as an HDD or SSD, the recommended format is Mac OS Extended; you also have the option of Mac OS Extended (Journaling). If you're formatting for an older Mac, or formatting a drive to use on an older Mac, choose Mac OS Extended.

Differences between exFAT and NTFS

NTFS (New Technology File System) is a log-based file system developed by Microsoft, featuring:

• The logging feature was covered in the previous section.
• The hard link feature allows different filenames to point directly to the same content.
• The compression feature automatically compresses any files moved to or saved in a folder with this feature enabled.

The detailed comparison between exFAT vs NTFS is as below:

Conclusions

This extensive article covers everything you might want to know about the macOS exFAT file system. You should now have a pretty solid understanding of macOS exFAT. I hope all the solutions above help you fix the exFAT not mounting issue on macOS. Despite its lack of logging, it's still a better option when formatting USB drives or SD cards. Based on the whole comparison section in this article, you can decide for yourself which one to choose between exFAT, Mac OS Extended, and NTFS.