How do I recover the MBR on a Thinkpad t420?

Question

After a messy Linux upgrade of my dual boot Lenovo T420 I ended up with GRUB replacing my MBR. Everything works fine: I can boot both Linux and Windows; the only thing different from before is that pressing the blue "Thinkvantage" button at boot time no longer starts recovery mode but just pops up a BIOS settings menu.

As far as I can tell my partitions are laid out like this

(primary) SYSTEM_DRV (?)
(primary) Windows7_OS
(logical?) Partitions I created
   (data partitions)
   (linux partitions)
(primary) Lenovo_recovery

My guess is that previously my system booted off the SYSTEM_DRV partition which just started the Windows7 partition if no key was pressed or the Lenovo_Recovery partition if the "Thinkvantage" button was pressed.

Any idea how I can revert to that configuration?

Answer 1

The only easy way to do this is with the Lenovo recovery DVDs (and you'd be looking a complete reimage then so it's largely impractical). If you didn't burn these when you got the system you'd be looking at purchasing them from Lenovo, which last I checked was about US$50.

I have no idea how difficult it is to get that partition booting with any OTHER bootloader - there may not be anything particularly special about it in and of itself, but I don't know of any way for you to get it to respond to that Thinkvantage keypress. Fortunately, there's not much of use on that recovery environment that you can't get in other ways anyway.

Answer 2

Lenovo uses a custom MBR so that the thinkvantage button works properly, as Shinrai stated one way to get it working again is a reimage of the hard drive using the Lenovo recovery discs.

Some brands like HP, you can mark the recovery partition as "active" and reboot, this will allow it to boot directly into the recovery partition and load recovery, this is the manual way to recover the notebook when the mbr has been replaced with a stock windows mbr. Not sure if this works on a Lenovo with a grub boot loader installed.

The recovery partition is bootable, you just need to figure out how to boot from that partition to run recovery if you don't have the recovery discs.

Most people make the recovery discs, then delete the recovery partition.

Answer 3

Can you boot with Windows 7 recovery disk and then do:

Boot to a dos prompt and from the Win7 DVD, in the boot folder, try running

bootsect /nt60 c:

Then run 'diskpart' and type type following

list disk
select disk 0  // Where disk 0 is where your C is
list partition
select partition 1 //Where partition 1 is C
active
exit

Reboot your system

EDIT: By DOS prompt I mean off the win7 DVD to a console, whatever they have

Answer 4

We should thanks Bill Gates to give us an utility called bootrec.exe to recover the MBR in the easiest possible way it could be. So here is the magic:

STEP1: Get Your USB bootable with window 7 on it. If you Do not know how to make the USB bootable, then follow this link.

STEP2: Reboot PC and boot from USB.
STEP3: Start Window 7 repair and you will come to a window that has command prompt option to open.
STEP4: Write the following code in the command prompt window to know the label of volume of USB:

x:\sources>diskpart
diskpart>select disk 0
diskpart>list volume
...

some entries will be shown. Select the volume of "Removable type" and remember the drive letter. For mean time, let's call that "x:"
Now, write following code into same window:

...
diskpart>exit
Leaving diskpart....
x:\sources>bootrec /fixmbr

and you are done. Now you have repaired your MBR and grub loader will no longer be a problem.