Recover a corrupted exFAT volume under OS X

I have a external drive that is formatted as exFAT. It does not show up on my system when I plug it in. When I run Disk Utility, the drive appears on my system but I get the following message:

Updating boot support partitions for the volume as required.

Error: Disk Utility can’t repair this disk. Back up as many of your files as possible, reformat the disk, and restore your backed-up files.

I then ran fsck_exfat in a terminal and got the following:

sudo fsck_exfat /dev/disk2s1
Password:
fsck_exfat: Opened /dev/rdisk2s1 read-only
** Checking volume.
** Checking main boot region.
** Checking system files.
** Volume name is 2tb_WD.
** Checking upper case translation table.
** Checking file system hierarchy.
fsck_exfat: Couldn't read 131072 bytes at offset 302667137024: Input/output error

How can I recover the data on the external hard drive?

2 Answers

I have had lot's of problems with exFat and OS X (especially if the disk isn't securely disconnected). Disk Utility was never able to fix my drive. However a simple fix disk errors with Windows 7/8 would fix the problem immediately and make the drive work again with OS X.

"fsck_exfat: Couldn't read 131072 bytes at offset 302667137024: Input/output error" ruh ruh raggy....

IO errors are usually VERY bad and could indicate a hardware failure - anything from bad clusters (which arn't too bad), bad cables (which are annoying) right down to gradual, complete, irrecoverable failure. , and at this point I'd urge you to backup whatever thats in that drive that means anything to you.I'd use ddrescue (probably available over something like macports or fink) and/or copy anything that means anything in whatever way possible and available to you (I've manually copied out files where even ddrescue failed), check disk health, then reformat the disk.