Re: [luau] bootable raid and the MBR

[R. Scott Belford]

Thanks a lot for the answers, Eric.  On a Friday night this little 
thread does not make very interesting reading.  I am okay with how the 
system boots now, it just seems like a bit of a compromise to have the 
mbr residing on a single IDE drive when I should have it on the 
redundant SCSI RAID array.

One would think that I could just remove the IDE drive and the 
installation would of course presume that the mbr is supposed to be on 
the remaining SCSI RAID drives in the system.  It's just that the 
installation won't start without the IDE drive.  Adaptec, the makers of 
this RAID controller, don't see why there should be a problem.  Tyan, 
the motherboard makers, of course figure it must be a controller issue.  
The fstab was a good suggestion, but I can't adjust the MBR parameters 
there.

I think that I will go back to it a bit later tonight, reset the 
motherboard, and boot with only the array.  I am also going to see if 
another OS will boot with only the raid controller present.  Then I am 
going to sing karaoke to it.  Sometimes you gotta get wicked.

Is it the bios that originally determines which drive to take a slice 
from for the MBR, or is it the first OS one installs?

scott


On Friday, May 24, 2002, at 08:06 PM, Eric Hattemer wrote:

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" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
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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