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Thread: Dualboot Two Hard Drives

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  1. #1
    Join Date
    Dec 2005
    Ubuntu 10.04 Lucid Lynx

    Dualboot Two Hard Drives

    This guide only applies to Ubuntu 9.04 and earlier versions, which use legacy grub. Later versions use grub2, which is significantly different, but grub2 has a much better automated detection of other OSes. There are several excellent Grub2 guides that you might want to consult, if you're using Ubuntu 9.10 or later:

    As a beginner, I wanted to set up a dual boot without installing Grub to windows and was able to find two excellent links for doing this:

    The excellent instructions provided by "lha" worked flawlessly for installing on 2 IDE drives.

    I also found links to dualboot with a SATA and an IDE drive:
    The above IDE + SATA threads are probably outdated, but I'll leave them FYI.

    Hope this helps someone looking for an alternate method of dualbooting with 2 hard drives...

    I have my personal computer set up to dualboot using the method described in the first two links, lha has give me his "blessings" to write up a HowTo with his instructions. This is an alternate method of dualbooting Ubuntu and Windows, using 2 hd, without installing grub to Windows or altering your Windows installation.

    First, disconnect your Windows drive, then connect the drive you want to install Ubuntu on as the primary IDE master drive. After installing Ubuntu, allow the updater to install all the necessary updates, this may take awhile. Shutdown your computer and reconnect your Windows drive as slave, then restart, your computer will boot into Ubuntu.

    You will need to edit your menu.lst file:
    (Open a terminal, copy & paste one line at a time, press "enter" each time)

    cd /boot/grub
    sudo cp menu.lst menu.lst_backup
    gksudo gedit menu.lst
    The first line changes to the grub directory, the second line makes a backup of your menu.lst file, and the third line opens the menu.lst file using the gedit text editor.

    Copy and paste the following lines above the line
    title              Windows XP
    root               (hd1,0)
    map                (hd0) (hd1)
    map                (hd1) (hd0)
    chainloader        +1
    If grub gives an error when rebooting, you can try rootnoverify (hd1,0) instead of root (hd1,0) in the second line.

    Note: If you prefer Ubuntu to boot by default, you can copy & paste the above entry at the very end of your menu.lst, instead of above ###BEGIN AUTOMAGIC....

    To automatically display the grub menu at bootup, find the line
    and replace with

    To adjust the time grub is displayed at bootup, change the timeout(in seconds)...I'd suggest 10 seconds(default is 3).

    Quit and save settings.

    Note: If for some reason you need to restore your original menu.lst:
    cd /boot/grub
    sudo cp menu.lst_backup menu.lst
    Reboot your computer, it will automatically boot to Windows, unless you choose Ubuntu within the time grub is displayed.

    If you want to uninstall Ubuntu, you can make the Windows drive primary master and reformat or unplug the Ubuntu drive.

    If you want to remove Windows, then you can unplug the Windows drive or reformat it, then open menu.lst

    gksudo gedit /boot/grub/menu.lst
    and remove the Windows entry in grub.

    Installing on a Dell Dimension 4550:
    I tried the above method trying to set up a dualboot on my Dell Dimension 4550, but when I tried to boot into Windows, I got "Error 21:Selected disk does not exist".
    I finally was able to get it to work by:
    Boot into Ubuntu, open up a terminal:
    sudo fdisk -l
    The -l is a lowercase "L"
    cat /etc/fstab
    From these two commands, I was able to determine that hdb, which was the slave drive with windows actually had 2 partitions. The first partition was a 35 Mb Dell utility and the second partition was Windows, so I changed the Windows root from (hd1,0) to (hd1,1) in the /boot/grub/menu.lst. However, I continued to get the error21 message...I thought maybe the jumper settings on the slave drive were incorrect. Fortunately, I entered bios setup by pressing "F2" during bootup and found out that the Primary ide controller for hd1 was turned "off" by default...I changed it to "Auto" detect. Grub booted directly into Windows and I'm enjoying dualboot of Windows and Dapper on my Dell computer.

    It is possible to set up a dualboot with Windows & Ubuntu on separate hard drives, with both hard drives connected during the install of Ubuntu:
    if you want to be absolutely sure not to overwrite your Windows mbr, then disconnect your Windows drive during Ubuntu installation.

    An excellent tool to download before installing Ubuntu is the Super Grub Disk:
    the Super Grub Disk is capable of restoring Windows mbr or reinstall grub...and can boot either Windows or Ubuntu.
    Last edited by confused57; April 19th, 2010 at 04:51 PM. Reason: Instructions


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