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Oleh Prypin
Asked: 2010-12-23 13:50:40 +0800 CST

How to avoid problems when installing Ubuntu and Windows 7 in dual-boot?

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I want to try out Ubuntu (and hopefully choose it as my primary OS). After looking at many versions of it in VirtualBox and from Live CD, I've finally decided to install it.

So I defragmented and shrinked one of the partitions to make room for Ubuntu.
My current setup (after shrinking the D: partition):

[·100 MB·] [······250000 MB······] [·······600000 MB·······] [··100000 MB···]
 Reserved   Windows 7 system (C:)          Data (D:)            Free space
   NTFS             NTFS                     NTFS              (for Ubuntu)

The Internet (including AskUbuntu) is full of scary stories about Windows not loading after installation of Ubuntu, something about installing GRUB to a wrong partition, etc.
As I am a newbie to Linux and Ubuntu, it is very easy for me to do something wrong. Please mention the problems that may appear and explain how to avoid them.

Ubuntu version that will be installed: 10.10 Desktop amd64

Please note that I have installed Windows 7 about a year ago, so I have much to lose if something goes wrong. I want to be very careful because there is no way for me to backup all the data.

10.10 grub2 dual-boot partitioning windows-7

4 Answers

  1. Best Answer

    Most of the scare your read about comes from an unlucky installation message from Grub that misled users to install Grub to their Windows partition boot sectors thus making Windows unbootable. As this is fixed now there is only a small risk left.

    If you take care not to touch your Windows partitions when installing Ubuntu, and if you follow the standard installation process provided with Ubuntu you are on the safe side.

    As always when installing a new OS or changing partitions backing up your data is absolutely necessary. I'm sure you have done that already.

    For deeper insights into dual-boot setups read the Community Wiki.

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  2. Backing up your data is essential. It looks like you have a separate data partition so that will facilitate the task. If the worst were to happen you could always restore Windows 7 from your original installation disk, and re-install all of your applications. Time consuming, but feasible.

    However, there is a way to backup your complete system, either the entire hard disk or each of the partitions in their "pre-install" condition. You would need to use disk imaging software and store the resulting disk images on a separate storage medium, e.g. an external USB drive (since you don't have a second internal drive). Then if your Ubuntu installation really went south, you could just restore the disk image and be back to your current system state in minutes - rather than in (many) hours.

    However, your initial work to set up the disk with lots of free space to hold Ubuntu should result in a completely trouble free operation and a working, dual-boot system.

    One potential issue that might - but probably won't (because you will like Ubuntu so much, you won't want to remove it) - occur is if you subsequently decided to dump Ubuntu and delete the partition. The chances are that you would eliminate the GRUB2 boot code and, since this will have essentially over-written the Windows' master boot record (MBR), your machine then would not boot. However, the fixes to such problems have been well described in a more recent post here on AskUbuntu. See: "How do I restore Grub after Windows has deleted it?" and the link provided by B. Roland to a tutorial on how to recover "unbootable" systems (http://ubuntuforums.org/showthread.php?t=1014708).

    But, as noted, your Ubuntu installation and dual-boot setup should go flawlessly.

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  3. From your description of your current set up, it seems as though C: and D: are on two separate drives. If this is correct, you can significantly enhance your safety by disconnecting the system drive before attempting to install; although this will prevent GRUB from finding the Windows installation. This is easily remedied, however.

    When you finish installing, reconnect your drive and set the BIOS to boot from the second one (which will now have GRUB installed). Boot into Ubuntu, and open a terminal to run sudo update-grub and it will recognize your Windows installation.

    You should then verify that /etc/default/grub (the GRUB configuration file) has GRUB_TIMEOUT set to something over 0 so you will see the boot menu. To open this file in a text editor (and edit it, if necessary), run gksu gedit /etc/default/grub. If you edited it, save the file and then run sudo update-grub again.

    Also, be sure that when you reach the phase of the installation where you are asked for a partitioning scheme you are absolutely certain of what you are telling Ubuntu to do. It will default to utilizing the entire disk, so be cautious. Otherwise, everything should be just hunky dory! If you run into any trouble, feel free to ask questions here. We'd love to see you become a member of our community!

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  4. Actually this is not an answer. I think answer is given above. I will just try to explain why this occurs.

    Every hard disk has a special tiny sector called Master Boot Record, which holds the boot information. When your PC boots, BIOS uses this information to boot the correct OS. Every Os installed on that hard disk must have an entry in MBR. For any linux distribution, they just write their entry alongside of other entries of OS, it's fair play. But for Windows, it totally erases all other entries in MBR except entries for windows OS (XP, Vista). So if you install ubuntu after windows, it will not erase other entries in MBR. So no problem occurs. But for windows, it erases all other entries. That's why, after installing windows you will never get your ubuntu (unless you fix it).

    For your case, you explicitly told the ubuntu installer to install ubuntu on the drive on which windows is located. As previous answers mentioned, just be careful when you chose the partition to install ubuntu

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