Mounting Ext2/Ext3/Ext4 USB Flash Drives on Mac: Read Only Success

As I've written in Mounting TrueCrypt Ext2/Ext3/Ext4 Volume on Mac: Read Only Success, it is possible to mount TrueCrypt volumes formatted as Ext2, Ext3, or Ext4.  It turns out the same software (TrueCrypt being optional) can let you mount USB Flash drives in those formats as well.

I could only get it to work in read-only mode though.  The software you'll need to install are, in this order:

1. OSXFUSE (2.6.0 at time of writing).  This is the successor to MacFUSE, which is no longer maintained and should be considered outdated.  Make sure to install the MacFUSE compatibility layer when installing OSXFUSE (you may have to choose this explicitly under custom install within the installer).
2. Fuse-ext2 (0.0.7 at time of writing).  More Fuse-ext2 documentation is available.

The tricky part is actually to find a USB Flash drive formatted correctly.  I did some testing on this, and found that technically, a USB Flash drive whose partition map scheme reads as Master Boot Record in Apple's Disk Utility program, equivalently, its partition type reads as W95 FAT32 in GNOME Disks (née GNOME Disk Utility, née Palimpsest), is required.  Then a volume created within that partition scheme that is formatted as Ext2, Ext3, or Ext4, can be mounted in read-only mode on a Mac (given the above two software are installed).

I could not get it to mount in read and write mode.

Note that if you format the drive in GParted - Gnome Partition Editor, it may inadvertently partition it in some Linux format that Macs cannot read at all (Mac OS X will prompt you to initialize the drive, thus erasing all data).  I used GNOME Disks to format just the volume to Ext2/3/4, without erasing and re-partitioning the disk.

In my opinion, the state of affairs of disk formats is really quite sad when it comes to cross-platform interoperability.  There is no easy to use, reliable, and modern file system that is full featured on all three major platforms: Windows, Mac, and Linux.  The closest is FAT file system, which is decidedly not modern.