This post is about how to install Debian GNU Linux from your hard disk, with the help of your Ubuntu GNU Linux operating system and without using CDrom, floppy, or any other removeable media.
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Then I tried to install Debian from hard disk and it worked smoothly. I think you can install Debian from any operating system but not from an NTFS partition. In my case, I installed it from Ubuntu and it was much easier this way because Ubuntu itself is a GNU/Linux/Debian based operating system. Instructions to do that are available on the official Debian Installer Manual (Debian Installer Manuals instructions are not Ubuntu specific but it does not matter). I would just try to make it a little more simpler. Please note that there are many other ways to do this, it will be a good idea to review other methods before trying this one.