View Full Version : ExFAT drive won't mount

Jan 12, 2013, 04:23 PM
I can't mount a USB 3 hard drive on either of my two macs. One is 10.7.5 and the other is 10.8.2. The drive is ExFAT formatted with a Master Boot Record (MBR). It mounts just fine on a Windows 7 PC, where it was formatted. I have another ExFAT MBR drive that works on all computers. Attached is a screenshot from Disk Utility, and this is what System Profiler says:

Capacity: 1.5 TB (1,500,301,909,504 bytes)
Removable Media: Yes
Detachable Drive: Yes
BSD Name: disk6
Product ID: 0x2320
Vendor ID: 0x0bc2 (Seagate LLC)
Version: 1.00
Serial Number: NA4G2DVT
Speed: Up to 480 Mb/sec
Manufacturer: Seagate
Location ID: 0x05100000 / 2
Current Available (mA): 500
Current Required (mA): 36
Partition Map Type: MBR (Master Boot Record)
S.M.A.R.T. status: Not Supported
Capacity: 1.5 TB (1,500,298,346,496 bytes)
File System: ExFAT
BSD Name: disk6s1
Content: Windows_NTFS
Volume UUID: 239B8B0D-222B-3B50-B147-FAC9ABFAFECB

Anyone know how to fix this in Mac OS X? It's interesting that the Content descriptor is Windows_NTFS. The drive is a Seagate Expansion Portable.

Jan 12, 2013, 04:26 PM
Format it using the Macs Disk Utility, single partition only.

Jan 12, 2013, 04:28 PM
Thanks, but it's a bit too late for that, now that it's full of important data. Are you certain that OS X can only read ExFAT volumes which were formatted by a Mac, or is that just a guess?

Jan 12, 2013, 04:33 PM
It sounds like some funky portioning.

FYI if the data's important you should have it backed up.

Jan 12, 2013, 04:35 PM
I wonder why it says "Content: Windows_NTFS"? Can you somehow check that the filesystem is pure ExFAT and didn't get modified somehow.

It shouldn't matter where it was formatted unless one of the formatting programs is buggy.

Jan 12, 2013, 04:36 PM
Yeah that does seem weird. Any ideas on how to check that?

Jan 12, 2013, 04:38 PM
Futzing around with the partition table can cause your data to vanish.

Back it up, reformat it using Disk Utility.