How-To: Mount an ext4
partition on macOS

Sometimes it may be necessary to mount a native Linux ext4 file system partition on your Mac to access the data. For example, if you are using an external USB 3.0 hard drive for backups of your NAS and want to access the data on a MacBook.

This guide describes the use of FUSE for macOS and ext4fuse to enable read-only access to the partition on macOS Mojave 10.14. It is recommended not to enable read-write access.

Install ext4fuse

You can install ext4fuse with Homebrew:

brew install ext4fuse

Find and mount the drive

Plug in the hard disk drive and list all available drives:

diskutil list

For an external drive, you should see something like this:

/dev/disk2 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *5.0 TB disk2
1: Linux Filesystem 5.0 TB disk2s1

Create an empty folder inside your home directory to avoid mounting as root:

cd ~
mkdir mnt
ext4fuse /dev/diskXsY mnt
ls -la mnt

diskXsY can be something like disk2s1. Instead of mnt, you can use another directory name.

Unmount

To unmount, run:

umount ~/mnt

Alternatively, click the eject button in Finder. You can run mount in the terminal to check that the ext4 file system is no longer mounted.

Permissions

It may be necessary to add your user to the _lpoperator group to get read access to the data. Replace bob with your macOS user name. You can get it with whoami.

sudo /usr/sbin/dseditgroup -o edit -a bob -t user _lpoperator

You can check membership with:

dseditgroup -o checkmember -m bob _lpoperator

This should return something like yes bob is a member of _lpoperator. Alternatively, you can add all users to the group:

dseditgroup -o edit -a everyone -t group _lpoperator

Alternative solutions

One alternative for accessing data from an ext4 file system is to use a Linux virtual machine, for example with VirtualBox, and mount the drive inside the VM. ext4 is natively supported by Linux, so that route can be safer if you need read-write access.

Additional notes

Be aware that there may be issues opening Synology .bkpi files on an ext4 partition. exFAT is usually smoother and natively supported on Windows and Mac, but for some NAS setups it requires an additional package. NTFS or HFS+ can be alternatives, but both may require additional software for cross-platform access.