[luau] bootable raid and the MBR

[Eric Hattemer]

Ok.  There's a lot of stuff here.  And I read it twice, but I'm still a
little lost.  One thing to keep in mind is that /etc/fstab mounts different
directories and such from hard drives it found.  The hard drives are
hard-coded in there according to where it finds them on the motherboard.  So
linux is never real happy about you moving drives around onto different
controllers.  Usually you'd have to use a bootdisk and manually change the
fstab.  That's probably a big part of your problem.  Second, I assume in the
HD controller bios setup, this isn't in raid array form or anything, right?
Its also conceivable, although not likely, that the hard drive controller
uses something weird like LBA or not LBA or something that makes it read
things differently than the standard controller.  The MBR is a special
little chunk of the hard drive that holds boot information.  If grub is in
the MBR, it should load grub, even if the OS is bad and doesn't support the
controller.  But here's three things to try.

1.  Install the OS again while the hard drive is on the raid array.  If it
loads the drivers, it should be perfectly happy with this.  Probably your
best option.

2.  Instead of grub, choose lilo to be your boot loader.  You may want to
use the LBA32 flag, or something like that that has some function in raid
arrays.

3.  boot off the install CD, enter rescue mode, figure out what device your
raid array is called, check your fstab, check your /etc/grub.conf, and make
sure it all works out ok.

-Eric Hattemer
----- Original Message -----
From: "R. Scott Belford" <sctinc at flex.com>
To: <luau at videl.ics.hawaii.edu>
Sent: Friday, May 24, 2002 6:46 PM
Subject: [luau] bootable raid and the MBR


> I have been getting spanked by something throughout the day that Adaptec
> and Tyan tech. support have bounced to each other.  I have built this
> aforementioned server with 2gb ram on Tyan's Tiger mboard with the MPX
> chipset for dual athlons.  The drive setup of choice is a raid5 scsi
> array controlled by Adaptec's 3210s controller.  For testing, moving
> things around, and for off disk archiving, I have placed an IDE drive on
> the secondary controller.
>
> Redhat's 7.3 install does a great job of recognizing and loading the
> drivers for the raid controller.  (7.2 required and expert install and
> loading the drivers from floppy)  The problem, of sorts, comes up when I
> choose where to put GRUB.  The MBR is on the IDE drive.  While I can
> boot this way, and, being a production server, rebooting ought not come
> up much, it is disturbing that I can't put the MBR on the drives that
> have the most reliability.
>
> I'm smart, so I think, and I'm smarter than this motherboard, so I
> think, so I take some action.  I take out the ide drive. (after ALWAYS
> disconnecting power cables) I reboot, make sure that the ide is gone
> from bios, adjust my boot order in bios to put the raid controller
> (which shows up specifically) second in line behind the cd rom, and I
> reboot.  Bios posts, raid controller posts, cdrom spins up to boot from,
> blank screen.  Reboot, Try again.  Reboot, Try again.  Reset bios to
> defaults, try again, reset bios eeprom or whatever that thing is, try
> again.  Each time I hear the cdrom spin up, I see the floppy drive light
> come on, and it is clear that my bios is searching the order I gave it
> to boot from.  It just won't boot anything.  Open case, disconnect raid
> array from controller, reboot, this time after posting, etc., the CD
> spins up and installation begins.  Damn.  Turn off box, reconnect array,
> reboot, cdrom spins up and system stays blank.  Curses.  Turn off,
> reconnect IDE drive, reboot, CD spins up this time and installation
> begins.  While in Disk Druid I notice this little slice on the ide drive
> before the two partitions I put there earlier.  It is my MBR.  My
> computer seems to like it.  So does my install CD.  My CD only boots
> when it is there.  I don't like it as much because it is not where I
> want it.  I curse the MBR.
>
> Adaptec says that it is supposed to boot and there must be something
> wrong with the mboard.  Tyan says they get this alot and that I need to
> make sure my controller is BBS or something like that, compliant.  I
> wrote the acronym down at work, but I am not there.  Apparently the
> controller is compliant, that's why I can see it specifically in Tyan's
> bios boot order.  The problem here may not be with either.  The problem
> may be with scott :-)
>
> I have a question after all this, I think.  How can I put the MBR on the
> RAID array?  I have never had to "put" and MBR anywhere, but perhaps I
> must boot from a floppy and format the mbr or something.  I don't think
> that I can boot with a win98 floppy and run fdisk mbr to do this.  Is
> there something comically easy that I am missing?  Does any wise soul
> have a suggestion or some insight into this?  You know, come to think of
> it. I did not try to boot with another installation CD.  Surely this
> couldn't be an issue, could it?
>
> I curse the MBR
>
> scott
>
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