I am not sure why, but here was my solution.
I determined through a lot of poking that the Master Boot Record of each
drive. Here is what I found out:
1. My backup drive (ad0) had the FreeBSD boot manager installed.
2. My main drive (twed0) had the FreeBSD MBR installed.
So, what is the problem? All I could figure is to install the boot manager
(called boot0cfg) onto my main drive. Silly, but it worked.
Why, I don't have a clue. I do, by the way, remember purposely using this
setup when I ran sysinstall to configure this machine. I felt that the ad0
drive needed a boot manager (just in case it was used someplace else) and the
main drive would not need a boot manager. But nothing ever indicated to me
that a standard MBR on twed0 would not work if ad0 was missing.
Here is my partition table from twed0:
# /dev/twed0
g c60801 h255 s63
p 1 0xa5 63 976768002
a 1
Notice there is just one partition and it is active. But it wouldn't boot
until I ran:
bootcfg -B twed0
which keeps the slice table the same.
Once I was done, the server will now boot with or without the ad0 drive. In
case of a backup drive failure, I had to also mess with fstab:
1. I had to add the "noauto" option, as someone suggested.
2. I had to disable all fsck passes (3 didn't work -->0) or fsck failure will
boot single user.
My question is now, do I write a script to mount the drive (too late, I did)
during boot and then to run fsck also? I am not sure how fsck should be run,
but I assume it is kind of important.
My main challenge was determining when to mount the disk. Here is my solution
and my script so far that seems to work.
=====================
#!/bin/sh
# mounts my special drive
# TODO: Need to fsck it
# PROVIDE: mountbackup
# REQUIRE: mail
# KEYWORD: nojail
. /etc/rc.subr
name="mountbackup"
start_cmd="mountbackup_start"
stop_cmd=":"
THIS="/disk250"
HOSTNAME=`/bin/hostname`
mailto=r...@${hostname}
TOD=`/bin/date`
mountbackup_start()
{
local err
# Mount "backup" filesystems.
echo -n "Mounting $THIS Backup filesystems"
mount $THIS
err=$?
echo '.'
case ${err} in
0)
;;
*)
echo "Mounting $THIS filesystems failed," \
" but it's okay for now. Sending mail to $MAILTO"
(echo " Mounting $THIS filesystems failed on boot!"
echo " "
echo "Host: $HOST Date: $TOD" | \
mail -s "FAILURE to mount $THIS on $HOST" $MAILTO
;;
esac
}
load_rc_config $name
run_rc_command "$1"
=====================
Billy Newsom wrote:
Nathan Vidican wrote:
> To me, it sounds like you have two issues to deal with here:
>
> #1 - booting off of the twed0 disk, what is your systems' BIOS currently
> set to boot from, from the way you describe it's almost as if the system
> is booting from ad0 - in which case yes, you will have to put a valid
> boot config onto twed0
I feel that I have run across a common and old "SCSI v IDE" battle (The
FreeBSD Handbook still talks about it). Even though I make the drive
controller (the twe = 3Ware SATA controller) as my first boot drive in
BIOS (effectively 0x80 as I understand it), FreeBSD does not ever pay
attention to the BIOS's numerical order. (See my reason below*) It wants
to find stuff on ad0 and boot that drive if it exists.
My supposition is that since I had twe0 and ad0 running during my 7.2
install, that the correct drive partition and MBR stuff were applied to
get it to boot AS-IS, but...
When it is not as it is now, It freezes at the boot loader, attempting
to find ad0.
It is either
a. Finding ad0 in fstab and really wishing it was there
or
b. The boot strap code is physically on ad0 and not twed0 because the
Sysinstall process never wrote it there.
I think it is b. If b, the boot process may be:
Stage 1: BIOS picks twe0 to be the first drive to attempt a boot.
Stage 2: MBR (boot 0) -- located on twe0
Stage 3: boot1 -- located on twed0 (BTX Boot Loader?)
Stage 4: boot2 -- located on ad0 (FreeBSD/i386 bootstrap loader 1.1?)
Stage 5: Boot Loader -- shows menu on twed0s1a
Stage 6: Kernel boots up on twed0s1a
And so when I remove ad0 to simulate a backup drive failure, the stage 4
tries to run a missing bootstrap loader from twed0.
Stage 4: boot2 -- missing on twed0, system hangs.
I think this is happening because it is the BTX loader which may find
and concatenate the BIOS drives, getting confused, and switching the
boot to ad0 for just the one stage that finishes the bootstrap.
I think one solution is to (next time) not install my backup drive until
after Sysinstall is long done! I think it's a sysinstall bug, some of this.
* My Reason for saying that is my guess that the sysinstall program saw
the ad0 as something important, and included it in the chain of the
boot. For example, when I was done SLICING my drives in Sysinstall, the
silly thing then got the "w" write command and went out there and made
some (wrong) decisions under the assumption that ad0 would NATURALLY
(via BIOS) be part of the boot process. So the right code never got
written to twe0 in the right places. Sure, it got all the kernel and I
told it to put a standard FreeBSD MBR, but it must be missing something
on track 0.
> #2 - you could add the flag 'noauto' to ad0 from within fstab - this
> will allow the system to boot without mounting the disk (alleviating the
> dreaded single-user-mode). Use a startup script in /usr/local/etc/rc.d
> to then mount the disk if available on bootup. I've done similar setups
> to this before where we were using external USB drives for backup and
> weren't 100% sure they'd always be connected in the case a server might
> be rebooted - worst case, you'll end up with it not mounted, but the
> system will still be up at least.
I will give it a try. I need to do something to correct this second
issue for certain. My ad0 is a good spare, but it's old.
> --
> Nathan Vidican
> nat...@vidican.com <mailto:nat...@vidican.com>
>
>
> On Fri, Jan 22, 2010 at 12:53 PM, Billy Newsom <bi...@nlcc.us
> <mailto:bi...@nlcc.us>> wrote:
>
> I am doing a test run on a production server. It has 2 hard drives.
>
> ad0 (mounted on /disk250 in a single slice plus SWAP)
> twed0 (mounted on / /var /usr and a SWAP)
>
> The twed0 is a hardware mirror and my main drive.
> ad0 is just for backups.
>
> What the issue is, and you probably know where I'm heading. The boot
> process freezes if I remove the ad0 (to test a drive failure
condition)
>
> It freezes after saying:
> BTX boot loader.... etc.
>
> FreeBSD/i386 bootstrap loader 1.1
> It spins for a second, then stops... unless I have ad0 in the
computer.
> /boot/kernel/kernel text=0x7b03a0 data=0xcdee0 /
>
> And it never gets to the boot menu.
>
> So:
>
> 1. Should I put a new boot0config on the twed0 drive? If so do I
> boot from a CD to do that?
>
> I need to potentially do something also to my disk labels and my
> fstab so that I don't boot to single user mode if drive ad0 fails. I
> haven't done this exact type of thing before, so I am looking for a
> little help.
>
> my fstab:
> /dev/ad0s1b none swap sw 0
> 0
> /dev/twed0s1b none swap sw 0
> 0
> /dev/twed0s1a / ufs rw 1
> 1
> /dev/ad0s1d /disk250 ufs rw 2
> 2
> /dev/twed0s1e /tmp ufs rw 2
> 2
> /dev/twed0s1f /usr ufs rw 2
> 2
> /dev/twed0s1d /var ufs rw 2
> 2
> /dev/acd0 /cdrom cd9660 ro,noauto 0
> 0
>
>
> I tried to read the MBR from the twed0 drive, and the program
> couldn't read it. The one from the ad0 drive is readable and I saved
> a copy of it.
_______________________________________________
freebsd-questions@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-questions
To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org"
