HOWTO: Restore GRUB (if your MBR is messed up)

[dannyboy79]

if you can boot into grub one time and then the next you can't, reinstalling grub will not solve this issue as it's not with grub. there's some other underlying issue with your current setup. what is the error? when you say grub hangs, where does it hang? it only hangs when trying to boot to ubuntu but not windows? do you have a multiple drive setup or just 1 hard drive which both os's on it? these are some of the questions that need to be answered. but no matter what you have to think about it, if grub works one time, then it doesn't the next, then it does the next, than that means that all of grubs files are there and it's loading so i don't think the issue is with grub.

[lukon]

It hangs in GRUB at the GRUB prompt.

The computer is Windows98se on HD0 and Ubuntu Dapper Drake on HD1 with GRUB in the MBR on HD0.

[petoro]

if you can boot into grub one time and then the next you can't, reinstalling grub will not solve this issue as it's not with grub. there's some other underlying issue with your current setup. what is the error? when you say grub hangs, where does it hang? it only hangs when trying to boot to ubuntu but not windows? do you have a multiple drive setup or just 1 hard drive which both os's on it? these are some of the questions that need to be answered. but no matter what you have to think about it, if grub works one time, then it doesn't the next, then it does the next, than that means that all of grubs files are there and it's loading so i don't think the issue is with grub.

I've restored the grub following the guide by dannyboy79, but without success.

My grub also works some of the times that I start the computer.

I have Tribe 5 and Vista Ultimate. (Also the Vista Bios emulator Loader 2.2.0 installed for experimental purposes.)

But I think I have found a pattern and now I know when Grub is going to fail:

If the last system I run was Ubuntu then grub works fine in the next boot.

If the last system I run was Vista then grub fails in the next boot, and I have to switch off the computer or restart with the power button.

(In this last case, grub works fine again.)

So, it is a run of the Vista operating system what makes grub fail in the next boot, and grub "magically" works again in the following boot.


Any hint to solve the grub fail after a Vista run?


Petoro

[dannyboy79]

I've restored the grub following the guide by dannyboy79, but without success.

My grub also works some of the times that I start the computer.

I have Tribe 5 and Vista Ultimate. (Also the Vista Bios emulator Loader 2.2.0 installed for experimental purposes.)

But I think I have found a pattern and now I know when Grub is going to fail:

If the last system I run was Ubuntu then grub works fine in the next boot.

If the last system I run was Vista then grub fails in the next boot, and I have to switch off the computer or restart with the power button.

(In this last case, grub works fine again.)

So, it is a run of the Vista operating system what makes grub fail in the next boot, and grub "magically" works again in the following boot.


Any hint to solve the grub fail after a Vista run?


Petoro

here's a very similar problem and solution to yours. check it out
http://ubuntuforums.org/showthread.php?t=391194&page=3

[petoro]

here's a very similar problem and solution to yours. check it out
http://ubuntuforums.org/showthread.php?t=391194&page=3

I'm not sure that I can find there a solution for my problem. I only have a hard disk with three partitions.

Anyway:

I've found that the grub error only happens after having closed Vista properly.

I've had the opportunity to see this after a Vista crash. I've had to close Vista by turning the computer off and then on again. And grub behaved well this time.

So, it is something that Vista makes at closing time what makes grub fail in the next boot.


Petoro

So, it is something that Vista makes at closing time what makes grub fail in the next boot.
Petoro

And it is something that grubs makes when it fails at the beginning what "magically" restores the proper grub functionallity again.

Very estrange. Any clue to mend this?


Petoro

Well, I have found a solution at last.

I was tweaking the settings on Turbo Memory (or Robson Memory or whatever it's called).

I did two things at once (not sure which of them got the problem solved):

1. I disabled the AHCI setting in the BIOS of the computer.
2. I actualized the Intel controller for Turbo Memory.

I activated AHCI again and the problem kept solved. The Grub has never failed again.

And thumbs down for the Turbo Memory technology, I've had to painfully turn off and then on the computer scores of times to get it functioning. In spite of that, I haven't noticed any improvement with it.


Petoro

[erusfatum]

hey guys, i have some problems and cant figure out whats wrong i had problems with windows xp, and had to reinstall them.
then i did as it was said, boot from the ubuntu cd, sudo grub, find /boot/grub/stage1, it gave me hd0.2 and hd1.5, so i did root (hd0.2), setup (hd0) and quit, restar but nothing, boots in to xp directly so i did it again but with root (hd1.5) but still the same, boots directly to xp how can this be solved? ive got 2 hds, one with 2 windows partitions, and ubuntu, and the other drive (i took it out from another pc to backup before installing windows again) with one partition ext3 for backup stuff, and fedora
thanks in advice

Edit: silly me, when i did root (hd1.5) i had to do setup (hd1) now every thing works fine

[mahasmb]

Restore GRUB quite simple in Ubuntu, instead going through all the "gain root access" and play with shell commands, you can use the Ubuntu installation CD to restore it without going through all kinds of hassles.

Here are the steps:

1. Boot your computer up with Ubunto CD
2. Go through all the process until you reech "[!!!] Disk Partition"
3. Select Manual Partition
4. Mount your appropriate linux partions

/
/boot
swap
.....

5. DO NOT FORMAT THEM.
6. Finish the manual partition
7. Say "Yes" when it asks you to save the changes
8. It will give you errors saying that "the system couldn't install ....." after that
9. Ignore them, keep select "continue" until you get back to the Ubuntu installation menu
10. Jump to "Install Grub ...."
11. Once it is finished, just restart your computer

Good luck!.

I'm a little confused with this. Are you saying that we should boot with the CD and then click on "Install" ?? But the fact that we don't format any partitions means nothing but GRUB will be changed/installed?

Edit: And would it make a difference if I have Feisty installed, but use a Dapper Drake CD??

[Czar]

With the Feisty CD, this 'trick' doesn't seem to work. Feisty fights with you until you format something, else it never allows you to finish.

[carlosponti]

What about a dual boot system with windows xp on partition and Ubuntu on the other? will installing grub the way described repair the loader to xp and Ubuntu or will it only work for a straight Ubuntu system.

[flarkit]

With the Feisty CD, this 'trick' doesn't seem to work. Feisty fights with you until you format something, else it never allows you to finish.

Oh dear, this is worrying.

I have a 160Gb disk with 3 partitions, for XP (OS + Apps + Data). I added a 250Gb with 5 partitions (XP-pagefile + Linux swap + / + /home + Shared-data)

Now Grub has cleverly gone and installed itself on the 160Gb, instead of the 250Gb. I suppose this is due to the BIOS pointing to the 160Gb as the boot disk. I'd hoped to leave the 160Gb untouched by the Linux install, so I plan to use the XP CD to fixmbr and fixmbr, to return the XP mbr. Now, I'd hoped to be able to switch the BIOS's boot-disk setting and reinstall Grub to the 250Gb's MBR.

Is it still possible to boot from the Feisty LiveCD, then install Grub, following the suggestions in the thread "How to install Grub from a live Ubuntu cd"?


edit:
Definitely some confusion here. If I set the 250Gb as the boot-disk, then Grub has no idea where anything is. Booting into the LiveCD and running "find /boot/grub/stage1", finds the same details as already stated, even though the partitions are quite different. I'll have to delve a little deeper, so that I can correctly dual-boot, without having Grub installed on my XP disk's MBR