[SOLVED] exFAT - invalid VBR checksum - partitionless volume

J

Just

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Jan 16, 2016
Posts
46
Hi!

How-to repair an exFAT volume, which was formatted as a single block device, i.e. without a partition table? The whole volume is used by exFAT, there is no MBR nor GPT on it. The volume reports an "invalid VBR checksum", and cannot be mounted (it is not attached to any drive letter).

Should I use Chkdsk.exe to repair the volume? How to do it, with the volume not attached to any letter?
Thanks.
 
Could you please provide a screenshot of disk management window?

Is the volume part of an external storage device?
 
Hi,

Here is the screenshot.


Computer management.PNG



"mountvol" does not return a GUID for the volume, too:

Code: 
Possible values for VolumeName along with current mount points are:

    \\?\Volume{d73e19c5-6b6d-11ea-859e-806e6f6e6963}\
        C:\

    \\?\Volume{d73e19c6-6b6d-11ea-859e-806e6f6e6963}\
        D:\

    \\?\Volume{d73e19c9-6b6d-11ea-859e-806e6f6e6963}\
        E:\
 
Hello,

the volume which the damaged exfat file system is located on is identified as disk 1 by the disk manager, on the previous screenshot. Again, the volume has no partition table.

One can refer to it as a "partition", out of language habit, but for the sake of correctness, I point out once again that it is not a partition. It's a block device, the totality of which being formatted in exfat.

That is where I fear the main difficulty lies.
 
Are you looking to mount the device to get the data off it, or just looking to reformat it?

Invalid VBR checksum sounds like there's corruption on the drive, and exFAT isn't very good at dealing with corruption and repairing it.

Do you have access to/can you make a bootable Linux CD? If you don't have one already made, can you make an Ubuntu 18 Live CD?
 
Hello,

Tekno Venus said:
Are you looking to mount the device to get the data off it, or just looking to reformat it?
Click to expand...


Frankly, I was thinking of a third scenario: repairing the exfat file system and then keep using the volume as is. But if you recommend otherwise, I'll stand by your opinion.

Invalid VBR checksum sounds like there's corruption on the drive, and exFAT isn't very good at dealing with corruption and repairing it.
Click to expand...


Well, that's not good news. I can't figure out what could have caused the filesystem corruption. If exfat is not only hard to fix, but also easy to corrupt, it's better not to use it at all. I don't remember this kind of problem with FAT32, is it specific to exFAT?

Do you have access to/can you make a bootable Linux CD? If you don't have one already made, can you make an Ubuntu 18 Live CD?
Click to expand...


That is not a problem. The machine is dual-boot equipped with a Linux Mint system too. The use of both systems on the same machine is the primary reason for choosing exfat for the now failed volume. However, I'm afraid that check.exfat is incapable of any repair. Hence my post on Sysnative.
 
Repairing exFAT is harder than other filesystems - it tends to be better for usb sticks and removable drives than internal ones. I guess the reason for chosing exFAT was to make it readable across both the Linux and Windows install?

exFAT (and FAT32) tend to be easier to corrupt than filesystems like ext4 and NTFS as it's not journaling (Journaling file system - Wikipedia) which could help prevent corruption with power loss.

In you boot up into Mint, can you see if you've got exfatfsck installed, specifically 1.3.0? If not, do an apt-get install and install it. Find your partition device name (e.g. dev/sda1) and run extfatfsck <devicename>. That should test the partition for corruption and print out what it finds.

You can then try running it again with the -a flag, which will attempt to automatically repair the partition. Run it without the flag first so you can see what the corruption is like before you try and repair it.

Man page here for reference: Ubuntu Manpage: exfatfsck - check an exFAT file system
 
Well, thank you for your good advice.

Version 1.3.0 of fsck.exfat (part of exfat-utils) fixed the exfat partition as you had expected. The immediate previous version (1.2.8) which was installed by default, was unable to make any repairs, which is why I came to Sysnative for help. There is a kind of irony to have got the exFAT file system fixed by a Linux tool, after that Windows' own chkdsk.exe could not see the volume at all.

But after all, I am the one who sought the problems by formatting the volume without a partition table. Theoretically, there's nothing wrong with that. In practice, only OS.X and Linux are able to mount such an exFAT volume.

Thank you again.
 
RHEL8/WIN10 dual boot : WIN10 corrupted my exfat HDD
  1. RHEL8 booted me into Emergency mode
  2. I entered my root password
  3. then typed systemctl - which displayed my error (in red) such that my exfat HDD “mount failed” as I previously defined it in the /etc/fstab file to do so
  4. then typed q to quit the systemctl output
  5. then typed nano /etc/fstab and commented my custom line that mounts my exfat HDD on boot up by entering a # sign before the line; then typed ctrl-x to exit & y to write buffer (save) to file
  6. then typed reboot and waited
  7. RHEL8 booted up normally this time, and I logged in
  8. then I opened a terminal window, and then…
  9. typed sudo exfatfsck /dev/sda (which is the device of my exfat HDD)
  10. then the exfatfsck utility output detected a corruption on my exfat HDD
  11. then I typed y to confirm I wanted to repair the corruption it discovered
  12. then exfatfsck utility output stated that it repaired my exfat HDD
  13. then I manually mounted the repaired exfat HDD to its previous mount point (the location I commented out in my fstab) by typing sudo mount /dev/sda /mnt/HDD
  14. the mount utility output stated it successfully mounted
  15. I was then able to access my files on the exfat HDD
  16. Thank you for this forum!
 

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