No root file system is defined. Please correct this from the partitioning menu
 

From Ubuntu 11.04 installer. What does this mean? how do I do it correctly?

This sounds like a message that you would see while running the installer. That would have been a good fact to mention in your post.

If this is something that you are seeing while you are installing Ubuntu I am going to guess that you have selected a custom partitioning scheme. This requires you to make the decisions about how the disk is partitioned and how your partitions are mounted in the installed system.

When you make a custom partition scheme you first make space on the disk by reducing the size of an existing partition. Then you create a partition in the unallocated space. Then you select that partition and choose the mount point. It sounds like you did not perform this third step.

When you ask a question you should provide as much information about the circumstances as is possible. In this case if you encountered this problem while you were running the installer then you should have said this and you should have included the sequence of actions that you performed just prior to seeing this message.

Are you very new to Linux? If so, you should probably refer to Ubuntu's site for some installation assistance. THIS is a good place to start.

Please don't feel that I'm trying to brush you off. LQ.org is a wonderful resource for all GNU/Linux folks, but sometimes you have to do your own homework a bit to get some background, which will assist you to ask questions and seek necessary information in a more efficient way.

We're here to help, but the Ubuntu-provided support is where you should start your search.

Luck with it!

~Eric

...and at a minimum you need 3 partitions;
boot partition, /boot
root partition, /
swap

He has told us that he sees that in the installer.

Oooops. :redface:

No you don't. On a home system you are perfectly fine without a /boot-partition. You can even omit the swap-partition and use a swap-file instead.

Since you seem to be new to Linux I would recommend to use the option to let the installer decide the partitioning. Just be sure you have chosen the option to install alongside Windows if you don't want to get rid of your Windows installation.

And of course, before partitioning your disk take a backup of your data ( if you haven't done that already, which normally should be the case).

Agreed, and that will be the default option when the partitioner opens. Just select how much space you want to leave for the Windows partition and the installer does the rest.

Thanks

Thank you for the correction.

If Ubuntu 11.04 is the same or similar to 10.10, you should be looking at the Allocate Drive Space window. If you have a partition to use, you can click on it in the main window to highlight it, then click on the Change tab to edit it. You should see several options including Mount point. Click the down arrow to the right of Mount point and you should see the root symbol "/". Select it. If you don't have a partition available, click on free or unallocated space and click Add tab. You get the same window.