Can't boot after adding exfat hdd to fstab

[zilexa]

I had the exact same issue yesterday, xbian 1.0 beta 1.1, raspberry with 512mb. The harddrive is connected to the usb hub from modmypi.com. it's a usb powered harddrive, Western Digital. I don't want to experiment since I do everything remotely, it's the RPi at my parents place. But don't have a choice now. I already reinstalled xbian using the Windows installer.. now Xbian works again but I still need to do the static mount. Btw I have created a static mount many times for both ext4 and Exfat on several RPis never had any issues.

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Ha I just did this (after I had to reinstall XBian on SD card):
- created a folder /media/usb
- sudo umount /media/usb0 (since the harddive is automatically mounted at boot to usb0)
- added my mount to fstab, looks like this now:

Terminal

#
#
#
proc /proc proc defaults 0 0
LABEL=xbian-root-btrfs / btrfs subvol=root/@,thread_pool=1,rw,compress=lzo,noatime,autodefrag 0 0
LABEL=xbian-root-btrfs /home btrfs subvol=home/@,thread_pool=1,rw,compress=lzo,noatime,autodefrag 0 0
UUID=8B12-9112 /boot vfat defaults 0 0
UUID=bc1df18b-2fcd-4cbb-86c9-b193fb5f039b /media/usb ntfs-3g defaults,noatime,nodiratime,async,big_writes 0 0

- did not reboot, I just did sudo mount -a and it gives me this warning:

Terminal

xbian@xbian /media $ sudo mount -a
NTFS signature is missing.
Failed to mount '/dev/sda1': Invalid argument
The device '/dev/sda1' doesn't seem to have a valid NTFS.
Maybe the wrong device is used? Or the whole disk instead of a
partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?

How can I fix the NTFS sig?

EDIT: Googled a lot, seems like the bootsector must have been overwritten somehow. I don't understand how this could have happened, but it happened. I deleted the partition using fdisk and created a new exfat partition, formatted it using mkfs.exfat. Updated the UUID in /etc/fstab (it changed after deleting partition and creating new one). Now mount -a still fails!! but sudo mount /dev/sda1 /media/usb DOES work. I am completely lost can anyone shed some light on this?