How To: Reinstall Grub Boot Loader (FC6)

[richardbaxter]

How to Reinstall FC6 Grub Boot Loader;
[Eg this is required if a Windows XP reinstallation overwrote/disabled your FC6 Linux boot partition]

***disclaimer; advice offered with no warranty***

1. Insert FC6 DVD
2. Reboot PC
3. type 'linux rescue' when prompted
4. Accept standard options [Eg English]
5. select your Linux partition used during the original FC6 installation when Grub was originally installed (Eg SDA2)
6. when prompted, select allow write access [ie, NOT read only]
7. type 'chroot /mnt/sysimage' [as suggested by linux rescue]
8. type 'grub-install /dev/sda' [assuming you wish to use the Primary boot sector of sda - you will wish to use this if you installed it here during the original FC6 installation]
9. restart PC
10. Grub should load, and your previous grub settings [before you reinstalled Windows XP] should have remained

Richard

[ppesci]

When you are in the command line, try to type:

/sbin/fdisk -l

to see what partitions an drives are recognized by linux.

[rickhg12hs]

I've had a dual boot Vista/FC6 and now F7 laptop running for about 6 months with no problems. I used EasyBCD to extend the Vista boot loader to chainload GRUB on another partition. It's worked without incident for a long time.

Now, Vista still works normally (well, as it does), but after selecting my F7 option (from the Vista boot loader), the screen goes blank then "GRUB read error" appears in the upper left corner ... and that's it. A 3-finger reboot is required, no Fedora.

I've read a number of posts and it seems that the error is caused by STAGE1 not being able to properly load STAGE2. The Rescue CD has no problem mounting the partition and everything looks like it's there (including everything in /boot and /boot/grub)... just can't seem to boot it. 8-(

My F7 partition is /dev/sda5 or (hd0,4) in GRUB-speak. From grub I've tried:

root (hd0,4)
setup (hd0,4)

It seemed to complete normally, but the same "GRUB read error" message appears on boot.

Originally Posted by richardbaxter

How to Reinstall FC6 Grub Boot Loader;

8. type 'grub-install /dev/sda' [assuming you wish to use the Primary boot sector of sda - you will wish to use this if you installed it here during the original FC6 installation]

Is there a reason/way to try grub-install if I don't want to mess with the drives MBR? Will it do something that my grub commands above have not?

Since I get the "GRUB read error" message, does that mean the Vista boot loader has properly chained and GRUB began running? I.e., Vista hasn't hosed the F7 GRUB, right?

What should I try next? And, yes the Vista must stay (anything that doesn't kill you only makes you stronger). 8-)

Thanks for any consideration.

[richardbaxter]

NB this methodology appears to work for both EL5 and EL6 also.

...

Originally Posted by rickhg12hs

I've had a dual boot Vista/FC6 and now F7 laptop running for about 6 months with no problems. I used EasyBCD to extend the Vista boot loader to chainload GRUB on another partition. It's worked without incident for a long time.

I would not recommend using the Windows Boot Manager to start anything other than Windows. I personally install Grub as my primary boot manger (on the primary boot sector).

Ideally, Windows is installed first, and then Linux (eg EL5/EL6) is installed (with grub) - which generally overwrites the Windows boot sequence. Grub automatically detects the Windows partition and adds to grub.conf the necessary command to load it.

However, if Windows is installed after Linux, grub can be extended to load the windows partition (eg XP, Win7) by manually adding the necessary command to grub.conf.

Added are some examples of grub.conf windows boot commands below. "PARTITIONINDEX" in these examples should be set to the partition index of Windows. This should generally be "0" if Windows was installed first*. You should use the command "/sbin/fdisk -l" (referenced by ppesci) to determine/confirm the partition index of Windows (or the Windows Boot Manager). Note, there is no blank line between the line "title..." and the line "root...".

title Windows XP

root (hd0,PARTITIONINDEX)
savedefault
makeactive
chainloader +1

title Windows 7

rootnoverify (hd0,PARTITIONINDEX)
chainloader +1

* Note again; you shouldn't have to modify grub.conf at all if Windows was installed before Linux. However exceptions do exist. An example of an exception would be if you RE-installed Windows and Windows changed the partition in which it needed to initialise its boot sequence/manager. These things happen, from experience - particularly on laptops with pre-installed copies of Windows.

[salemeni]

Thank you for this tips.