No root file system is defined

Question

Here the steps I used to install Ubuntu.

1. Booted Ubuntu 13.04 from a USB drive (I have XP). Everything going fine. Gave me options how to install.
2. Chose "Other" as I have multiple drives. Gave me the option which drive to use.
3. Screen came up with all my drives and the partitions on each. (PS It would be REALLY useful if drive letters were included in the list!)
4. Highlighted the drive/partition I wanted to use: /dev/sdc2
5. Screen showed "Device for boot loader installation: /dev/sdc2 (So far, so good - I think)
6. Clicked on "Install Now" and get the message "No root file system is defined. Please correct this from the partitioning menu". BUT, doesn't tell me where the partitioning menu is! I double clicked on the drive/partition I want to use, and a small "Edit Partition" window opens. I assume this IS the partitioning menu.
7. Allows me to change the size of the partition (it should already be big enough). "Use as" I had set up as NTFS (There were 10 choices to pick from. From some of the comments on here it sounds like I should be using ext4. Is that right? Next line is a checkbox with "Format the partition". Didn't do that. It's a new partition.
8. Next line "Mount Point" I put /dos. Again from other comments on here it looks like I should be using / - right?

If I change the above to ext4 and / will it continue to install? Don't know what else to expect after this?

Answer 1

In Short

choose ext4 as file system (it's modern and ubuntu's default) and select the hard drive you want and set it up for "/". Be aware that you should back up all your data on this disk first, since it will be deleted (formatted).

Explanation

ext 4 is modern, stable and ubuntu's default so this is a clear recommendation. Ths Sign "/" is called "root". It's basically a folder, like c:\ in Windows. As you maybe know, paths of files in linux look like this:

/home/user/Desktop/example.txt or
/bin/bash

and this is why / (only the first sign) is called root. Because every file path begins with it. It's like the main folder that kind of has no name (obviously: "/"), so it's just called root.

Choosing "/" for this hard drive means that this hard drive will contain every folder of your file system, except the ones you want to have on other hard drives. You could for example choose another hard drive and say "be my /home/ folder". This way you can split up and customize your Ubuntu to work with many hard drives or SSDs to speed up your computer for example.

Well, and to show where the "c:\" equivalent "/" should be, you have to assign it to a disk. To show where to install linux, kind of.

Answer 2

There are two issues here: partitioning and boot device

Partitioning

Ubuntu needs a minimum of two partitions to work well: a root partition (labelled /) and a swap partition.

The way to change partitions in your case depends a lot on what you already have.

You can have only four primary partitions but you can have many logical partitions.

So, if you do not have four partitions on your disk, after choosing "something else" during installation, reduce the size of you largest partition to create free space. Then create two new partitions: a big one (10 Gb is a rough practical minimum) for your root partition. So choose / as mount point and a small swap partition (2-4 Gb).

P.S. Drive letters is something Windows arbitrarily assigns to partitions so the installation cannot guess them. Furthermore Linux doesn't use drive letters. Your first hard disk will probably be /dev/sda the second drive /dev/sdb, etc.

Boot device

The boot device you should choose is /dev/sda (your primary hard disk) and not /dev/sdaX.