Talk:Rescue and Recovery

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Revision as of 00:03, 30 October 2005 by Pebolle (Talk | contribs) (Should we discus a dissected MBR here?)

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"It is not known how to invoke Rescue and Recovery once GRUB has been installed in the master boot record."

See, Consideration 6:

 The Master Boot Record (MBR) must be configured properly for the 
 Rescue and Recovery application to function properly.  When possible, 
 the Rescue and Recovery application attempts to ensure the proper 
 configuration of the MBR.  This can only occur if the Rescue and 
 Recovery application is installed after other applications that 
 requires the MBR.

Apparently the R and R uses some very specific stuff in the MBR. Maybe Google will help you find some further info (has someone ever looked at the R and R enabled MBR in depth?)

Paul Bolle 13:43, 9 Oct 2005 (CEST)

Having special data in the MBR means less room for code, which may explain why the preinstalled MBR ignores the Active bit and (as far as I can tell) always boots the first partition. The latter means GRUB can't be installed in a partition boot sector either...

--Thinker 14:06, 9 Oct 2005 (CEST)

Why not? If the RnR-MBR always boots the first partition, just go back to the classical recommended partition layout (from the times that LILO didn't support LBA) and create a tiny first partition (that you can i.e. use as /boot partition, which has certain advantages). Install grub into that partition.

Wyrfel 14:44, 9 Oct 2005 (CEST)

I saw posts about the R&R software (or at least some versions thereof) assuming that the Windows partition is the first one.

--Thinker 14:52, 9 Oct 2005 (CEST)

Another hack you might try is to "rebrand" your first partition to some Windows type (I guess you should choose NTFS) without any other change to the fs! (So in reality it's still an ext3 fs or whatever.) If R and R is _non_ destructive (I wouldn't know!) it would be interesting to see how deeply it really checks the first partition. (It shouldn't check too deeply, as it should be able to "rescue" a messed up Windows partition, shouldn't it?)

But chances are this is a pointless hack ...

Paul Bolle 15:16, 9 Oct 2005 (CEST)

Is that true? That would mean you'd have to keep the Windows installation for the R&R system to work. In that case the only way to go would be installing grub4dos on that windows installation.

Wyrfel 14:56, 9 Oct 2005 (CEST)

Another idea/question. Shouldn't it be possible to copy an NT boot sector to a file via dd and chainload that file from GRUB? This way grub could go to the boot sector of the first partition and boot the NT boot sector that may then sit on a Linux filesystem, which in turn would boot the first partition.

Wyrfel 14:59, 9 Oct 2005 (CEST)

Could you please elaborate, Wyrfel? You lost me here ...

Paul Bolle 15:18, 9 Oct 2005 (CEST)

I think chaining GRUB from Windows will work (I don't know about grub4dos, but there's the trick of copying over the GRUB boot sector into a file and telling NTDETECT to load that.)

The trick with putting GRUB into the Windows boot sector and chaning into a copy of the original also sounds like it might work.

Alas, I can test neither, since I eliminated RNR from my disk after it stopped working even with the original MBR restored. No idea why. IBM sure didn't work very hard to make RNR 3.0 compatible with the standard partitioning and boot conventions...

--Thinker 16:12, 9 Oct 2005 (CEST)

I mean the reverse approach of this.

Copy the NT boot sector into a file, place that file on a linux partition, boot into the file via grub. I don't know if this could at all work. First, grub might not be able to chainload a file, though i believe it is, second, the NT boot sector may not like to be a file. AFAIK, the NT boot sector knows the partition it is suppossed to find NTLDR on. So it wouldn't depend on being the first sector of the same partition.

Wyrfel 01:27, 10 Oct 2005 (CEST)

Success booting R&R from GRUB

The method mentioned on the article (changing the partition type to 0x0b) worked for me on my T42.

You can do that with GRUB:

 parttype (hd0,1) 0x0b

You can add that to a GRUB menu entry that boots the recovery partition, which otherwise looks like this:

 title           IBM Rescue and Recovery
 root            (hd0,1)
 chainloader     +1

(Note that the Access IBM does not work during boot any more -- you have to explicitly choose the R&R partition from the GRUB menu. Good enough for me.)

I think that the recovery partition type is set to 0x12 to hide it from your Windows installation. The preinstalled MBR probably changes the partition type when you press Access IBM, and changes it back on next boot.

Grub for dos is the best solution:

R52 MBR for those who want to dissect it.

Hi there, I had the issue regarding the blue screen while trying to boot the IBM R&R partition, but the type-changing trick worked. I made a complete factory restore, and I was happy to discover that it fixed the MBR in such a way that the R&R PreDesktop area now works at all times. I've now made a backup of this MBR in case something ever happens (like accidentally putting a better boot loader in it ;-)). It looks quite different compared to a classic Windows XP made MBR, so it might be worth to take a look.

Anyway, for those interested, the R52 MBR can be downloaded here. 10:21, 28 Oct 2005 (CEST)

Thanks for the information. Question: "works at all times" here means:

a) when pressing the Access IBM / ThinkVantage / Whatever button

b) when booted by GRUB (chainloaded by NTLDR?)

c) ?

Paul Bolle 20:52, 28 Oct 2005 (CEST)

Yeah sorry, I could have been more verbose on that part. Actually, what I meant was that pressing the "Access IBM" button launches the R&R area successfully, regardless of the partition being of type 0x12 or 0xb. I'm fairly sure that if anything is changed in the MBR, R&R will be broken once more. I guess some very specific stuff is initialized within the master boot code. I can't risk experimenting with it for now, as the laptop in question isn't mine to begin with.

Also, note that pressing the button doesn't give any other options, apparently. It just immediately boots the R&R partition. When the MBR was tampered with, pressing the button would give a boot menu, where one could choose to enter the BIOS menu, or boot another device. The only way to boot into R&R was to use a separate bootloader (in my case, a GRUB boot CD). 23:19, 28 Oct 2005 (CEST)

It would be rather nice to dissect and discus that MBR. But I'm not sure whether we should encourage to do that on ThinkWiki. Any opinions (other than mere slogans such as: "We should have freedom to tinker!") on this subject would be greatly appreciated. Admins?

Paul Bolle 01:03, 30 Oct 2005 (CEST)