gptsync: GPT partition of type 'Unknown' found, will not touch this disk.

[Red Nelb]

Alright, I tried again, and kept the results this time.

Should I add the $ sign after the chroot thing or not? I tried both, although none worked.

This time I also saved it in the right place I believe (I did right-click / save link as/ file system / root (it said the folder was last modified at 17:00, which was exactly when I entered the last few commands).

Here is what I got:

To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.

ubuntu@ubuntu:~$ sudo mkdir /mnt/root
ubuntu@ubuntu:~$ sudo mount -t ext4 /dev/sda4 /mnt/root
ubuntu@ubuntu:~$ sudo mount -t proc none /mnt/root/proc
ubuntu@ubuntu:~$ sudo mount -o bind /dev /mnt/root/dev
ubuntu@ubuntu:~$ sudo chroot /mnt/root /bin/bash
root@ubuntu:/# $ sudo dpkg --install gptsync*deb
$: command not found
root@ubuntu:/# sudo dpkg --install gptsync*deb
sudo: unable to resolve host ubuntu
dpkg: error processing gptsync*deb (--install):
cannot access archive: No such file or directory
Errors were encountered while processing:
gptsync*deb
root@ubuntu:/#

EDIT: okay, I found /mnt/root now, altough when I try saving the package into it I get this:

"Error opening file '/mnt/root/gptsync_0.13-10_i386.deb': Permission denied"

[kevpatts]

just sounds like you're not using sudo with your dpkg command.

I was able to boot into Ubuntu by using the Option (Alt) key, and bypassing rEFIt, but then when I updated grub, and removed rEFIt, but then when I booted into Ubuntu again the screen just fills with the word GRUB GRUB GRUB GRUB repeatedly.

Not having any luck yet. going to use GParted live cd to remove all non-mac os partitions and restore the mac os x partition to the full drive capacity, and then start again.

[lhall]

Thanks for the help guys. The chroot command was giving me problems for some reason. But it seemed to work when i just switched in to super user. Now it seems to be all is well when i boot without rEFIit.

[kevpatts]

Glad you got it working.

I'm also keeping an eye on this thread as it's a similar issue for me.

[Red Nelb]

@kevpatts

What do you mean? I'm pretty much copy-pasting the said commands.

By the way, I'm trying to install 9.10, if that may be a source of problems.

I'll try bypassing rEFIt at this point I guess.

[Red Nelb]

Okay, so now I've gone through all the steps but nothing seems to have changed.

I still only see Mac Os X and a generic partition icon on rEFIt and the partition tool still isn't working.

Any idea on what is not working?

[mistermartin75]

I'm having similar problems. The partition tool doesn't work and I can only boot OS X, not the installed Ubuntu nor the Live CD. Tried installing rEFIt 0.12 but that doesn't even load.

Update: Knoppix to the rescue, once again. While Ubuntu always fails to boot from the Live CD when you actually need it, Knoppix never does. Started Knoppix, added Debian's sid repository and install gptsync. Ran it and everything worked!

[proycon]

I'm glad to see this thread solved the problem for several users.

Okay, so now I've gone through all the steps but nothing seems to have changed.

I still only see Mac Os X and a generic partition icon on rEFIt and the partition tool still isn't working.

Any idea on what is not working?

If you've gone through all steps correctly, then the "gptsync: GPT partition of type 'Unknown' found, will not touch this disk" error should at least be gone. Isn't this the case? If not, what was reported when you ran gptsync ? Running gptsync 0.13-10 (and no lesser version!) is the whole key here in resolving this problem. If you run gptsync twice, it should report that there is nothing to be done the second time around.

[Nohtanhoj]

This is what I did to get Ubuntu working: Nothing.

I figured that I was going to try the stuff in this thread (it all sounds like good advice), so I inserted my Live CD and held down Option as my Mac was booting (this looks for bootable devices by default). My main Mac OS X hard drive shows up, followed by the Live CD, and surprise, so does the Linux partition!!! I booted from it, set up my user account, and I'm typing from Ubuntu right now...

Even doubly better, if I just boot normally without holding down Option, my iMac boots to OS X and bypasses rEFIt (I was planning to do this anyway)...

I know it sounds pretty obvious, but I suggest you give this a quick try before you mess with your partition table... I didn't even try it consciously and it worked. =D

[phorque]

Oh, that is actually quite a good point which I completely overlooked in my earlier explanation. I think you'll have to chroot into your original distribution as otherwise it can't properly reinstall grub.

Here are revised instructions for the whole process:

( In this example I assume your disk is /dev/sda , default for macbooks, and your root partition is /dev/sda4 , adapt these if necessary! )

1) Download an Ubuntu Live CD ( see https://help.ubuntu.com/community/LiveCD ) and burn the ISO to CD.
2) Boot your macbook from the CD (hold option key at startup if you don't have rEFIt)
3) Open a terminal, mount your original root partition
- $ sudo mkdir /mnt/root
- $ sudo mount -t ext4 /dev/sda4 /mnt/root
4) Find the correct package for your architecture on http://packages.debian.org/sid/gptsync and download it to somewhere under /mnt/root/
5) Set up /proc and /dev
- $ sudo mount -t proc none /mnt/root/proc
- $ sudo mount -o bind /dev /mnt/root/dev
6) Chroot into your original system, you're now in your own system.
- $ sudo chroot /mnt/root /bin/bash
7) Install the package downloaded in step 4
- $ sudo dpkg --install gptsync*deb
8) Run gptsync on the affected disk
- $ sudo gptsync /dev/sda
9) Reinstall grub (this shouldn't overwrite rEFIt, but you can keep a copy of rEFIt on CD if you're concerned)
- $ sudo grub-install /dev/sda
10) reboot, the system should be able to boot again now

Hopefully it works for you, this is what I did in my situation as well.

The only part that doesn't make sense to me is installing grub to /dev/sda ... can't you install it to /dev/sda3 (as per the generic install instructions) if you still want to use rEFIt to select which system to boot into?