Hosed my MBR?

[Jerry McAllister]

> 
> On Tue, Apr 11, 2006 at 01:27:03PM -0400, Jerry McAllister wrote:
> > > 
> > > On Tue, April 11, 2006 09:08, Jerry McAllister wrote:
> > > >>
> > > >> I'm in a bit of a mess here.  I've got an Asus P4C800-E Deluxe
> > > >> motherboard with two on-board SATA RAID controllers, an Intel
> > > >> MatrixRAID (ICH5R) and Promise Fasttrak (PDC20378).  My BIOS
> > > >> allows me to boot from either the Promise or the Intel
> > > >> controller.
> > > >>
> > > >
> > > > Well, the install CD is also the fixit CD.  You can try booting
> > > > from it and choosing the shell and then trying to run the fdisk
> > > > from that environment to replace the MBR.
> > > >
> > > > I have done that for people who have hosed their MBR on machines
> > > > with Ghost - even their XP only, no FreeBSD, systems, using the
> > > > FreeBSD fixit, I ran fdisk and replaced the MBR with the FreeBSD
> > > > MBR and it worked just fine.
> > > >
> > > Hi Jerry,
> > > 
> > > I think the root of my confusion here is the fact that I have two
> > > RAID controllers and can boot off either controller.
> > > 
> > > Does that mean I have two MBR's, one for each controller?  If that's
> > > the case and I boot off a CD-ROM, which MBR am I fixing?
> > 
> > Are both controllers part of the same raid device?   
> >
> no, as I said in my OP, each controller hosts a RAID1.  The Intel has
> two disks for Win, and the FastTrak has two disks dedicated to FreeBSD.
> 
> > Anyway, there needs to be an MBR on each bootable device as well as
> > the boot files.   I think that holds true for raid setups as well.  
> > 
> > In addition, the first bootable device that your BIOS sees must have
> > an MBR regardless of whether you have 1 or more bootable devices.
> > 
> > In your case, it sounds like you have two raid devices, one on each
> > controller.   You would have to have an MBR on each and it sounds like
> > you think you wiped the one on the INTEL controller.   Figure out what
> > device name the raid on the INTEL controller comes up as and then
> > write the MBR to that.
> > 
> Thanks for your response.  My follow-up question to you is how would
> running a FBSD fdisk command on the Intel controller fix a hosed WinXP
> MBR?  Or is an MBR OS agnostic?

Well, the FreeBSD MBR is.   I have used a FreeBSD MBR to fix a hosed
MBR (hosed by Ghost) on an XP only (eg. no FreeBSD on it) machine and 
it worked fine.  

I suspect it might not work in the reverse direction, though.  The MS
MBR is not known for playing nice with other OS boot sectors.  I don't
know what the difference it.

Is there some other disk and [preferrably SCSI] controller you can 
stick in and install FreeBSD on and try to mount and check out the
raid that you think is hosed before doing anything irreversable?
I forgot if you said you had tried looking at it with a fixit disk
but that might work if the raid is hardware raid.

////jerry

> 
> -- 
> Regards,
> Doug
>