macos - Shared partition between OSX and Windows 10 (using Bootcamp) Disappeared?

Monday, September 15, 2014

macos - Shared partition between OSX and Windows 10 (using Bootcamp) Disappeared?

Longtime windows user giving OSX a go. My idea was to install Windows via BootCamp and have a shared partition that holds my Dropbox folder (to avoid having dropbox take twice the room on my SSD), music and some other media.

It wasn't a breeze to setup (this post helped me allot after my bootcamp disappeared when adding the shared partition in disk utility) but eventually I got it going. Today however after setting up Dropbox on Windows (not sure if coincidental) the shared partition disappeared and is not showing in either OS (I mean in Finder/File Explorer).

The Shared partition is the 250GB one and was formatted as ExFAT.

This is what Disk Utility is showing:

This is the output I am getting from GDisk:

GPT fdisk (gdisk) version 1.0.1
Warning: Devices opened with shared lock will not have their
partition table automatically reloaded!
Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present
Found valid GPT with protective MBR; using GPT.
Command (? for help): p
Disk /dev/disk0: 977105060 sectors, 465.9 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): E17AF55E-F8EF-4DE3-9767-F7CCC3C37CDC
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 977105026
Partitions will be aligned on 8-sector boundaries
Total free space is 262281 sectors (128.1 MiB)
Number  Start (sector)    End (sector)  Size       Code  Name
   1              40          409639   200.0 MiB   EF00  EFI System Partition
   2          409640       292336615   139.2 GiB   AF05  Untitled
   3       292336616       293606151   619.9 MiB   AB00  Recovery HD
   4       293606152       781438975   232.6 GiB   0700  Windows_NTFS_Untitl...
   5       781701120       977104895   93.2 GiB    0700  BOOTCAMP

Answer

So after much research I managed to resolve the issue. Looks like ExFAT is susceptible to corruption, but you can actually repair it in terminal. In hindsight it looks like a better solution would have been to format the shared drive as NTFS and use Paragon NTFS to read/write to the share in OSX.

Solution

If you encounter a similar issue with ExFAT under OSX, the steps to solve it are as follows:

Find out your partition identifier in Terminal by running the command

diskutil list

run the following command to repair the disk (replace disk0s4 with whatever your partition name is according to step 1)

sudo fsck_exfat -d disk0s4

The disk will be scanned and repaired (you will be prompted whether you want to repair).