I am sharing this solution, so that the people who have the same problem would be able find this thread through search engine and follow the advice
My Macbook Pro has two partitions:
first is "Mac OS X Extended (Journaled)" -- where Mac OS X is installed, and the
second has ~0.5 TB ExFat filesystem (for storing torrent downloads + other junk)
Recently, I have noticed the disappearance of ExFat partition from Finder,
and when I went to Disk Utility I was unpleasantly surprised: instead of ExFat partition,
all that I saw was disk0s4 grey partition which had "--" size, appeared as MS-DOS partition,
was impossible to mount, and when I tried to Verify/Repair it failed shamelessly!
The error log for this failure could be seen below (date/time removed for convenience):
Googling didn't reveal much, and although I have found some posts that suggested using chkdsk {drive letter}: /f command from Windows Bootcamp, that was not an option for me : I don't use Bootcamp+Windows, and for installing it I would have had to spend a lot of time and mess with still-alive Mac OS X partition, which was the least thing I wanted! Not to mention the fact that experienced Mac/Linux users should be able to accomplish their purposes without having to use Windows...
Then, I have found this wonderful article by Craig Smith,
which suggested to use sudo fsck_exfat -d disk0s4 terminal command.
It scanned this troubled partition and asked to update the boot region.
I agreed, and was told that the volume was repaired successfully.
Then, I have restarted the Disk Utility. Initially, it looked like the problem has not been fixed - grey disk0s4 MS-DOS zero-sized partition was still present. But this time I was able to successfully verify and repair the partition!
P.S. Some users have suggested that the Mac OS X implementation of ExFat support is somewhat buggy.
Here are related threads:
https://discussions.apple.com/thread/6602285?start=0&tstart=0
https://discussions.apple.com/thread/4154638?tstart=0&tstart=0
My Macbook Pro has two partitions:
first is "Mac OS X Extended (Journaled)" -- where Mac OS X is installed, and the
second has ~0.5 TB ExFat filesystem (for storing torrent downloads + other junk)
Recently, I have noticed the disappearance of ExFat partition from Finder,
and when I went to Disk Utility I was unpleasantly surprised: instead of ExFat partition,
all that I saw was disk0s4 grey partition which had "--" size, appeared as MS-DOS partition,
was impossible to mount, and when I tried to Verify/Repair it failed shamelessly!
The error log for this failure could be seen below (date/time removed for convenience):
Code:
**********
Disk Utility started.
Verifying volume “disk0s4”
Starting verification tool:
Checking file system
** /dev/disk0s4
Invalid sector size: 0
Error: This disk needs to be repaired. Click Repair Disk.
Disk Utility stopped verifying “disk0s4”: This disk needs to be repaired.
Click Repair Disk.
Verify and Repair volume “disk0s4”
Starting repair tool:
Checking file system
** /dev/disk0s4
Invalid sector size: 0
Volume repair complete.
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.
Disk Utility stopped repairing “disk0s4”: 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.
**********Googling didn't reveal much, and although I have found some posts that suggested using chkdsk {drive letter}: /f command from Windows Bootcamp, that was not an option for me : I don't use Bootcamp+Windows, and for installing it I would have had to spend a lot of time and mess with still-alive Mac OS X partition, which was the least thing I wanted! Not to mention the fact that experienced Mac/Linux users should be able to accomplish their purposes without having to use Windows...
Then, I have found this wonderful article by Craig Smith,
which suggested to use sudo fsck_exfat -d disk0s4 terminal command.
It scanned this troubled partition and asked to update the boot region.
I agreed, and was told that the volume was repaired successfully.
Then, I have restarted the Disk Utility. Initially, it looked like the problem has not been fixed - grey disk0s4 MS-DOS zero-sized partition was still present. But this time I was able to successfully verify and repair the partition!
P.S. Some users have suggested that the Mac OS X implementation of ExFat support is somewhat buggy.
Here are related threads:
https://discussions.apple.com/thread/6602285?start=0&tstart=0
https://discussions.apple.com/thread/4154638?tstart=0&tstart=0
