Repairing a Corrupted Mac OSX ExFAT Partition

ExFATI run a MacBook Pro Retina (late 2013) and on my 512GB hard drive I have 3 partitions

  • 150GB Mac OSX partition (currently running Mavericks)
  • 150GB Windows 8.1 partition (via Bootcamp)
  • 200GB data parition (formatted with ExFAT)

I chose an ExFAT partition so I could read and write to the data partition from either the OSX or the Windows partition as I use each operating system a similar amount. I had planned to install VMWare fusion at some point to avoid the dual boot, but haven’t sone so due to some licencing issues with some software on my Windows partition that I uncovered in the trial.

Recently I was travelling and was doing some editing for my podcast on the plane. I also inadvertantly moved and deleted some files. The next morning I woke up to deliver a workshop to find that my data partition was missing. Windows reported that the drive needed to be formatted and Mac OSX reported that the drive was corrupt. On either operating system, the relevant disk utilities were unable to fix the issue.

It appears that ExFAT partitions are not well supported in OSX, particularly if you delete files. Unfortunately due to Windows and Mac not playing nicely from a read/write perspective, neither HFS or NTFS are an option for this drive either.

A bunch of articles seemed to indicate that CHKDSK /F on the volume should fix it, but given the fact that Windows was reporting the partition needed to be formatted, this fix was not valid in this circumstance. After searching the web for numerous reports and fixes (and tearing my hair out with worry in the process), I finally stumbled on an article that led to a simple solution of a terminal command:

sudo fsck_exfat -d disk0s4

where diskos4 is your ExFAT partition.

It then asks:

Main boot region needs to be updated. Yes/No?

to which you reply Yes. You can then run repair in the OSX Disk Utility and the partition should be restored!

Easy fix, but baffles me why ExFAT and NTFS support is so bad on Mac OSX.