rEFIt, Linux and Windows on a MAC

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Level 1

4 points

rEFIt, Linux and Windows on a MAC

I recently thought that I nerfed my Windows installation, by mistakenly installing Linux (Ubuntu) after installing Windows. Next boot I got GRUB Hard disk error and could no longer boot windows, and the thought of reinstalling Windows infuriated me because I would have to spend half an hour or more on the phone with Customer Service to obtain a new Product Key to authorize a new installation.

Well, after much research, and some figuring out, I realised the MBR (Master Boot Record) Boot Code was set to GRUB. How do I get it back to normal I thought.

Well obviously obliterate your Linux install altogether is first step. Remove rEFIt because you need to boot up in single user mode, and that gets overridden by rEFIt's terminal program.

Once at prompt in single user mode type:

fdsk -u /dev/rdisk0

that will reset your MBR to default.

Next insert Windows installation when u get the choice to install or recover, hit R for recovery mode at the C:\ prompt type FIXMBR and enter.

exit and reboot and viola Windows boots up and all traces of Linux and GRUB gone.

Next project is to figure out how to clone my Windows installation safely and be absolutely positive that I can restore it. Since I would like Linux on my system. Unfortunately, I did not build an NTFS drive so Winclone not an option. I read somewhere that Disk Utility restore feature can do it, if I partition an external drive to same size as Bootcamp drive and format it to MS-DOS and back it up to that.

Anyway, I think FIXMBR is a possible fix to Disk Read Errors, as I would imagine the DREs are related to the MBR being borked.

Message was edited by: Magiccam

iMac, Mac OS X (10.5.1)

Posted on Dec 20, 2007 9:35 AM

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Answer 1

Jan 4, 2008 11:02 AM in response to Magiccam

Does that erase the content of the windows (or mac) partition?

Do I type "fdisk -u /dev/rdisk0" after the GRUB error message or in terminal on the mac?

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Answer 2

Jan 4, 2008 10:50 PM in response to Magiccam

I answered my own question.

For those of you (like me) who aren't sure how to do this:
1 - make sure your boot disk is set to your Macintosh Partition (in the system prefs)
2 - shut down your mac
3 - hold down the "apple" key and the "s" key
4 - while holding this down turn on your computer (and keep holding this key combination until a black screen with white text appears)
5 - wait until this screen stops changing (it's done loading)
6 - type in *fdisk -u /dev/rdisk0* and press enter
7 - it may ask you if you want to make a new MBR, if it does type y and press enter
8 - once it has finished, type exit and press enter
9 - it will return to mac os X, (without bluetooth until you restart.

Part 2---------

1 - insert your Windows install disk
2 - restart your computer and while your computer boots (and before the apple logo appears) hold down the "alt/option" key until there is an icon of your hard drive and the cd-rom
3 - select the cd and press enter
4 - the cd will boot. It might ask you if you want to boot from the cd. push any key before the (and push it soon or else you will have to start part 2 over again)
5 - it will load (for a while)
6 - go get a snack because it takes about 5 minutes to load
7 - when a screen asks you if you want to install or repair, choose repair (push R)
8 - choose your disk (most likely number 1) and push enter
9 - if you have a password set, you will need to type it in. (I had trouble and the password turned out to be the password I had before my current password.)
10 - type in FIXMBR and push enter
11 - It might give you a warning, type y and push enter
12 - type exit and push enter

You can now boot to XP and osX

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Answer 3

MacStevo

Level 1

0 points

Jan 16, 2008 8:26 PM in response to Magiccam

I have the same problem. I installed Vista Ultimate, and then rEFIt and Ubuntu. I erased Ubuntu, but I got that GRUB error like you. Then I deleted the rEFIt folders and such. Now when I boot into my Windows partition, I don't get the error message, but I don't get Windows either. I only get a blank screen with a blinking command prompt at the top left, but it doesn't even let me type anything. I tried everything you said here, but I still can't figure it out.

The strange thing is that when I look at my startup disks in OS X, the Windows option shows up. When I boot Windows from the DVD, my existing Windows partition shows up for recovery. But when I hold down alt while starting up, I only get the Macintosh HD option. Does anyone know what I can do to get Windows booting normally again? I really don't want to reinstall it.

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