Out Of disk, but still boots
Okay, so it seems to be a problem with GRUB. I found this info in the official Ubuntu documentation. I know you already know how to get going with boot repair, but I will include it in case you forgot, or someone else is having the same issue.
You can either download the boot repair ISO, burn it to a CD and boot from that, or you can use a regular Ubuntu Live CD. When using a regular Ubuntu Live CD you will need to:
boot your computer on a Ubuntu live-CD or live-USB.
choose "Try Ubuntu"
connect internet
open a new Terminal (Ctrl+Alt+T), then type:
sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update - Press Enter.
- Then type:
sudo apt-get install -y boot-repair && boot-repair - Press Enter
The information on getting boot repair also came from the Ubuntu documentation.
Now, fire up boot repair, click the Advanced options -> GRUB options tab, and check the ATA disk support (solves the [out-of-disk] error) option, then Apply. Reboot, and hopefully that will take care of the issue.
If still not good, create a separate /boot partition at the start of the disk: https://help.ubuntu.com/community/BootPartition
When one gets the Out of disk error, there are two solutions to try (in this order):
First try the
ATA disk supportoption of Boot-Repair as described by reverendj1, then reboot. This is very easy, but it does not always solve the problem.Then, if still not good, create a little separate /boot partition at the start of the disk. See https://help.ubuntu.com/community/BootPartition
For more information, see the tutorial that describes the procedure for installing Ubuntu on a big disk: https://help.ubuntu.com/community/InstallingUbuntuOnBigDisk