Well I got the problem partially solved; and I thought it would be a
worse situation than it was.  The partial solution I found at
http://www.pendrivelinux.com/grub-error-21-after-full-install-to-usb-hard-drive/
  and consists of

sudo fdisk -l

to get a list of partitions and to find out where you want the primary
grub to be.   In my case (SATA) sda and sdb, in other cases (EDI) hda,
hdb, hdc, etc.  I wanted it to be on sda and not sdb (which it
defaulted to).

Then

sudo grub-install /dev/sdx

where x is the drive from which you wish to boot.

In my case

sudo grub-install /dev/sda

to fix the problem.

Then reboot.  You will no longer be able to boot from the external
drive....  Unless, and I haven't tried this yet....  I change the boot
order in my Bios to boot from the external drive before booting from
the hard drive.   I still have to check this out.  Be back shortly.

On Wed, Jan 21, 2009 at 10:45 AM, Mike Bigalke <[email protected]> wrote:
> I installed Ubuntu 8.10 on an external hard drive yesterday.  Somehow
> during the install Grub dHecided to default to the external drive and
> I now get an error 21 when I try to boot without the USB drive
> attached.  I tried changing the BIOS to default to the internal drive
> before the external USB; it didn't work.  I thought maybe editing
> menu.lst on the internal would work.  Then I was struck by the idea
> that maybe it actually defaults to and demands that the external drive
> Grub program be present due to some low level change on the internal
> hard drive and there I am.  Stuck.  Any ideas on how to get Grub to
> default back to the internal hard drive?
>
>
>
> Here is my menu.lst from the external hard drive.
> # menu.lst - See: grub(8), info grub, update-grub(8)
> #            grub-install(8), grub-floppy(8),
> #            grub-md5-cryptr/share/doc/grub
> #            and /usr/share/doc/grub-doc/.
>
> ## default num
> # Set the default entry to the entry number NUM. Numbering starts from 0, and
> # the entry number 0 is the default if the command is not used.
> #
> # You can specify 'saved' instead of a number. In this case, the default entry
> # is the entry saved with the command 'savedefault'.
> # WARNING: If you are using dmraid do not use 'savedefault' or your
> # array will desync and will not let you boot your system.
> default         0
>
> ## timeout sec
> # Set a timeout, in SEC seconds, before automatically booting the default 
> entry
> # (normally the first entry defined).
> timeout         10
>
> ## hiddenmenu
> # Hides the menu by default (press ESC to see the menu)
> #hiddenmenu
>
> # Pretty colours
> #color cyan/blue white/blue
>
> ## password ['--md5'] passwd
> # If used in the first section of a menu file, disable all interactive editing
> # control (menu entry editor and command-line)  and entries protected by the
> # command 'lock'
> # e.g. password topsecret
> #      password --md5 $1$gLhU0/$aW78kHK1QfV3P2b2znUoe/
> # password topsecret
>
> #
> # examples
> #
> # title         Windows 95/98/NT/2000
> # root          (hd0,0)
> # makeactive
> # chainloader   +1
> #
> # title         Linux
> # root          (hd0,1)
> # kernel        /vmlinuz root=/dev/hda2 ro
> #
>
> #
> # Put static boot stanzas before and/or after AUTOMAGIC KERNEL LIST
>
> ### BEGIN AUTOMAGIC KERNELS LIST
> ## lines between the AUTOMAGIC KERNELS LIST markers will be modified
> ## by the debian update-grub script except for the default options below
>
> ## DO NOT UNCOMMENT THEM, Just edit them to your needs
>
> ## ## Start Default Options ##
> ## default kernel options
> ## default kernel options for automagic boot options
> ## If you want special options for specific kernels use kopt_x_y_z
> ## where x.y.z is kernel version. Minor versions can be omitted.
> ## e.g. kopt=root=/dev/hda1 ro
> ##      kopt_2_6_8=root=/dev/hdc1 ro
> ##      kopt_2_6_8_2_686=root=/dev/hdc2 ro
> # kopt=root=UUID=773dfc5d-50e2-41ff-856e-6792808e3d19 ro
>
> ## default grub root device
> ## e.g. groot=(hd0,0)
> # groot=773dfc5d-50e2-41ff-856e-6792808e3d19
>
> ## should update-grub create alternative automagic boot options
> ## e.g. alternative=true
> ##      alternative=false
> # alternative=true
>
> ## should update-grub lock alternative automagic boot options
> ## e.g. lockalternative=true
> ##      lockalternative=false
> # lockalternative=false
>
> ## additional options to use with the default boot option, but not with the
> ## alternatives
> ## e.g. defoptions=vga=791 resume=/dev/hda5
> # defoptions=quiet splash
>
> ## should update-grub lock old automagic boot options
> ## e.g. lockold=false
> ##      lockold=true
> # lockold=false
>
> ## Xen hypervisor options to use with the default Xen boot option
> # xenhopt=
>
> ## Xen Linux kernel options to use with the default Xen boot option
> # xenkopt=console=tty0
>
> ## altoption boot targets option
> ## multiple altoptions lines are allowed
> ## e.g. altoptions=(extra menu suffix) extra boot options
> ##      altoptions=(recovery) single
> # altoptions=(recovery mode) single
>
> ## controls how many kernels should be put into the menu.lst
> ## only counts the first occurence of a kernel, not the
> ## alternative kernel options
> ## e.g. howmany=all
> ##      howmany=7
> # howmany=all
>
> ## should update-grub create memtest86 boot option
> ## e.g. memtest86=true
> ##      memtest86=false
> # memtest86=true
>
> ## should update-grub adjust the value of the default booted system
> ## can be true or false
> # updatedefaultentry=false
>
> ## should update-grub add savedefault to the default options
> ## can be true or false
> # savedefault=false
>
> ## ## End Default Options ##
>
> title           Ubuntu 8.10, kernel 2.6.27-7-generic
> uuid            773dfc5d-50e2-41ff-856e-6792808e3d19
> kernel          /boot/vmlinuz-2.6.27-7-generic
> root=UUID=773dfc5d-50e2-41ff-856e-6792808e3d19 ro quiet splash
> initrd          /boot/initrd.img-2.6.27-7-generic
> quiet
>
> title           Ubuntu 8.10, kernel 2.6.27-7-generic (recovery mode)
> uuid            773dfc5d-50e2-41ff-856e-6792808e3d19
> kernel          /boot/vmlinuz-2.6.27-7-generic
> root=UUID=773dfc5d-50e2-41ff-856e-6792808e3d19 ro  single
> initrd          /boot/initrd.img-2.6.27-7-generic
>
> title           Ubuntu 8.10, memtest86+
> uuid            773dfc5d-50e2-41ff-856e-6792808e3d19
> kernel          /boot/memtest86+.bin
> quiet
>
> ### END DEBIAN AUTOMAGIC KERNELS LIST
>
> # This is a divider, added to separate the menu items below from the Debian
> # ones.
> title           Other operating systems:
> root
>
>
> # This entry automatically added by the Debian installer for a non-linux OS
> # on /dev/sda1
> title           Windows Vista/Longhorn (loader)
> root            (hd0,0)
> savedefault
> makeactive
> chainloader     +1
>
>
> # This entry automatically added by the Debian installer for a non-linux OS
> # on /dev/sda2
> title           Windows Vista/Longhorn (loader)
> root            (hd0,1)
> savedefault
> makeactive
> chainloader     +1
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sda5.
> title           Ubuntu 8.04.2, kernel 2.6.24-23-generic (on /dev/sda5)
> root            (hd0,4)
> kernel          /boot/vmlinuz-2.6.24-23-generic
> root=UUID=818f9ddc-a156-4240-ae16-5378b6cea4c5 ro splash vga=773
> initrd          /boot/initrd.img-2.6.24-23-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sda5.
> title           Ubuntu 8.04.2, kernel 2.6.24-23-generic (recovery mode) (on 
> /dev/sda5)
> root            (hd0,4)
> kernel          /boot/vmlinuz-2.6.24-23-generic
> root=UUID=818f9ddc-a156-4240-ae16-5378b6cea4c5 ro single
> initrd          /boot/initrd.img-2.6.24-23-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sda5.
> title           Ubuntu 8.04.2, kernel 2.6.24-22-generic (on /dev/sda5)
> root            (hd0,4)
> kernel          /boot/vmlinuz-2.6.24-22-generic
> root=UUID=818f9ddc-a156-4240-ae16-5378b6cea4c5 ro splash vga=773
> initrd          /boot/initrd.img-2.6.24-22-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sda5.
> title           Ubuntu 8.04.2, kernel 2.6.24-22-generic (recovery mode) (on 
> /dev/sda5)
> root            (hd0,4)
> kernel          /boot/vmlinuz-2.6.24-22-generic
> root=UUID=818f9ddc-a156-4240-ae16-5378b6cea4c5 ro single
> initrd          /boot/initrd.img-2.6.24-22-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sda5.
> title           Ubuntu 8.04.2, kernel 2.6.24-21-generic (on /dev/sda5)
> root            (hd0,4)
> kernel          /boot/vmlinuz-2.6.24-21-generic
> root=UUID=818f9ddc-a156-4240-ae16-5378b6cea4c5 ro splash vga=773
> initrd          /boot/initrd.img-2.6.24-21-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sda5.
> title           Ubuntu 8.04.2, kernel 2.6.24-21-generic (recovery mode) (on 
> /dev/sda5)
> root            (hd0,4)
> kernel          /boot/vmlinuz-2.6.24-21-generic
> root=UUID=818f9ddc-a156-4240-ae16-5378b6cea4c5 ro single
> initrd          /boot/initrd.img-2.6.24-21-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sda5.
> title           Ubuntu 8.04.2, kernel 2.6.24-19-generic (on /dev/sda5)
> root            (hd0,4)
> kernel          /boot/vmlinuz-2.6.24-19-generic
> root=UUID=818f9ddc-a156-4240-ae16-5378b6cea4c5 ro splash vga=773
> initrd          /boot/initrd.img-2.6.24-19-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sda5.
> title           Ubuntu 8.04.2, kernel 2.6.24-19-generic (recovery mode) (on 
> /dev/sda5)
> root            (hd0,4)
> kernel          /boot/vmlinuz-2.6.24-19-generic
> root=UUID=818f9ddc-a156-4240-ae16-5378b6cea4c5 ro single
> initrd          /boot/initrd.img-2.6.24-19-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sda5.
> title           Ubuntu 8.04.2, kernel 2.6.24-18-generic (on /dev/sda5)
> root            (hd0,4)
> kernel          /boot/vmlinuz-2.6.24-18-generic
> root=UUID=818f9ddc-a156-4240-ae16-5378b6cea4c5 ro splash vga=773
> initrd          /boot/initrd.img-2.6.24-18-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sda5.
> title           Ubuntu 8.04.2, kernel 2.6.24-18-generic (recovery mode) (on 
> /dev/sda5)
> root            (hd0,4)
> kernel          /boot/vmlinuz-2.6.24-18-generic
> root=UUID=818f9ddc-a156-4240-ae16-5378b6cea4c5 ro single
> initrd          /boot/initrd.img-2.6.24-18-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sda5.
> title           Ubuntu 8.04.2, kernel 2.6.24-17-generic (on /dev/sda5)
> root            (hd0,4)
> kernel          /boot/vmlinuz-2.6.24-17-generic
> root=UUID=818f9ddc-a156-4240-ae16-5378b6cea4c5 ro splash vga=773
> initrd          /boot/initrd.img-2.6.24-17-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sda5.
> title           Ubuntu 8.04.2, kernel 2.6.24-17-generic (recovery mode) (on 
> /dev/sda5)
> root            (hd0,4)
> kernel          /boot/vmlinuz-2.6.24-17-generic
> root=UUID=818f9ddc-a156-4240-ae16-5378b6cea4c5 ro single
> initrd          /boot/initrd.img-2.6.24-17-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sda5.
> title           Ubuntu 8.04.2, kernel 2.6.24-16-generic (on /dev/sda5)
> root            (hd0,4)
> kernel          /boot/vmlinuz-2.6.24-16-generic
> root=UUID=818f9ddc-a156-4240-ae16-5378b6cea4c5 ro splash vga=773
> initrd          /boot/initrd.img-2.6.24-16-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sda5.
> title           Ubuntu 8.04.2, kernel 2.6.24-16-generic (recovery mode) (on 
> /dev/sda5)
> root            (hd0,4)
> kernel          /boot/vmlinuz-2.6.24-16-generic
> root=UUID=818f9ddc-a156-4240-ae16-5378b6cea4c5 ro single
> initrd          /boot/initrd.img-2.6.24-16-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sda5.
> title           Ubuntu 8.04.2, memtest86+ (on /dev/sda5)
> root            (hd0,4)
> kernel          /boot/memtest86+.bin
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for a non-linux OS
> # on /dev/sdb2
> title           Windows Vista/Longhorn (loader)
> root            (hd1,1)
> savedefault
> makeactive
> map             (hd0) (hd1)
> map             (hd1) (hd0)
> chainloader     +1
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sdb3.
> title           Ubuntu 7.10, kernel 2.6.22-14-generic (on /dev/sdb3)
> root            (hd1,2)
> kernel          /boot/vmlinuz-2.6.22-14-generic
> root=UUID=d6d52470-6775-41b9-814a-778b47ed37ba ro quiet splash
> initrd          /boot/initrd.img-2.6.22-14-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sdb3.
> title           Ubuntu 7.10, kernel 2.6.22-14-generic (recovery mode) (on 
> /dev/sdb3)
> root            (hd1,2)
> kernel          /boot/vmlinuz-2.6.22-14-generic
> root=UUID=d6d52470-6775-41b9-814a-778b47ed37ba ro single
> initrd          /boot/initrd.img-2.6.22-14-generic
> savedefault
> boot
>
>
> # This entry automatically added by the Debian installer for an existing
> # linux installation on /dev/sdb3.
> title           Ubuntu 7.10, memtest86+ (on /dev/sdb3)
> root            (hd1,2)
> kernel          /boot/memtest86+.bin
> savedefault
> boot
>

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