Why I cant read/mount on macosx external disk formatted extfat?

Question

I have connected via USB this SATA disk previously mounted on a Linux system in a RAID 1 HW configuration:

I have installed ext4fuse to mount the FS.

First of all I checked the drive with:

 diskutil info -all

     Device Identifier:         disk2
     Device Node:               /dev/disk2
     Whole:                     Yes
     Part of Whole:             disk2
     Device / Media Name:       EARX-00PASB0

     Volume Name:               Not applicable (no file system)
     Mounted:                   Not applicable (no file system)
     File System:               None

     Content (IOContent):       FDisk_partition_scheme
     OS Can Be Installed:       No
     Media Type:                Generic
     Protocol:                  USB
     SMART Status:              Not Supported

     Disk Size:                 2.0 TB (2000398934016 Bytes) (exactly 3907029168 512-Byte-Units)
     Device Block Size:         512 Bytes

     Read-Only Media:           No
     Read-Only Volume:          Not applicable (no file system)

     Device Location:           External
     Removable Media:           Fixed

     Solid State:               Info not available
     Virtual:                   No

  **********

     Device Identifier:         disk2s1
     Device Node:               /dev/disk2s1
     Whole:                     No
     Part of Whole:             disk2

     Volume Name:               Not applicable (no file system)
     Mounted:                   Not applicable (no file system)
     File System:               None

     Partition Type:            Windows_LDM
     OS Can Be Installed:       No
     Media Type:                Generic
     Protocol:                  USB
     SMART Status:              Not Supported
     Partition Offset:          32256 Bytes (63 512-Byte-Device-Blocks)

     Disk Size:                 2.0 TB (2000388063744 Bytes) (exactly 3907007937 512-Byte-Units)
     Device Block Size:         512 Bytes

     Read-Only Media:           No
     Read-Only Volume:          Not applicable (no file system)

     Device Location:           External
     Removable Media:           Fixed

     Solid State:               Info not available

  **********

Looking around I then tried the following commands:

sudo ext4fuse /dev/disk2  ~/tmp/MY_EXT_PARTITION -o allow_other

Partition doesn't contain EXT4 filesystem

Then:

diskutil verifydisk disk2

Unable to verify this whole disk: A GUID Partition Table (GPT) partitioning scheme is required (-69773)

Also :

sudo gpt -r show /dev/disk2

     start        size  index  contents
         0           1         MBR
         1          62
        63  3907007937      1  MBR part 66
3907008000       21168


sudo gpt recover /dev/disk2
gpt recover: /dev/disk2: error: device contains a MBR


diskutil repairDisk /dev/disk2
Unable to repair this whole disk: A GUID Partition Table (GPT) partitioning scheme is required (-69773)

I have actually no other clue on how to access this disk. Do you have some ideas?

EDIT

on a ubuntu machine the disk is readable and the file system type is

fsck -N /dev/sdb1
fsck from util-linux 2.20.1
 [/sbin/fsck.ext2 (1) -- /dev/sdb1] fsck.ext2 /dev/sdb1

How can I manage to make it readable on mac os x?

You're using ext4 and got tools for an exfat disk? Or it is extX? Or FAT? Can you check on a Windows machine? — LTPCGO, Jan 07 '20 at 18:03

Christophe Tcheng · Answer 1 · 2020-03-21T11:03:48.930

I'm in the same situation, and no linux box around.

A solution for me was to install vagrant/virtual box, then add the oracle virtual box extension pack (important to access USB2/3, without that the usb disk doesn't show up). Then pull ubuntu/xenial64: vagrant init ubuntu/xenial64 (or any other distro), and enable USB 3.0 in the VM setting (enable + filter). Launch the VM, and while the VM is running, plug the USB disk. Then normal sudo mount works great and you can copy contents to another place. You need to enable exfat (add universe to apt, update apt and then install ext4-fuse and ext4-utils).

Quite convoluted but at least I have the data! Hope it works for you.

Why I cant read/mount on macosx external disk formatted extfat?

1 Answers1