RAID creation fails due to absent package "mdadm"

I also had this issue. I searched Google after seeing that error and came to this page.

I fear most people wouldn't think of searching Google and would go back to Windows saying "Linux sucks" or "Ubuntu sucks" because they see an error that has very little meaning.

After further investigation, it appears as though this affects the Live CD only. The alternate install works perfectly with RAID array creation even when Ubuntu is installed.

It appears as though the Live CD does not officially support software RAID array creation, see: https://help.ubuntu.com/community/Installation/SoftwareRAID#Requirements

Though this is not made apparent to the user when creating the RAID array (gnome-disk-utility is there and it allows you to get as far as configuring the array).

We deliberately removed mdadm from the default installation several releases ago; it makes the boot process slower and more complex, and for most people without RAID arrays it's just a waste of disk space. Of course, it's installed if you have a RAID array available during installation. The desktop CD explicitly does not yet support RAID, although it may do in the future.

ok, so install mdadm : sudo apt-get install mdadm

BTW, if you have started using the Palimpsest Disk Utility, your disks may already have been partitioned for the RAID. If so, you can't use Palimpsest to remove the partitions.
Use Gparted to clean up the mess and remove any partition.

Then go back to Palimpsest to create your raid. Now, mdadm will work :)

While most people who are trying to create a RAID array are probably perfectly capable of figuring out the problem, it's just the usability is terrible and reflects poorly on the program. It would seem reasonable for the program to validate that the user has the necessary has software installed (in this case mdadm) when trying to perform an action before the dialog for that action is even displayed. Not a show stopper, but definitely some low hanging fruit for anyone who has the source hanging around.

My live system froze after reporting the 'mdadm not found' error. This happened twice. The first time, it happened before I was able to read the error message. The second time, it froze as I was scrolling the error message in to view. This issue deserves some attention.

I have this problem after doing an install from the alternative CD 11.10 so it'snot just isolated to the live CD.

mdadm may well have been removed for speed reasons, but then Disk Utility needs to fail gracefully and not as it does show that mdadm completed successfully.

Please don't be fooled that everyone that might come across this can fix it, I have never done raid on Linux before and I am still learning, and struggling after 2 days (i.e. 2 days after first attempting to create an RAID array its still not functional). Issues like mdadm and Disk Utility not working nicely together, do indeed make me wish for the days when I used to do this in Windows with a huge amount of comparative ease.

Jason this bug is about gnome-disk-utility, a GUI application for managing disks, not have having a dependency on mdadm so that one can create RAID arrays. The alternate installer doesn't have a GUI and doesn't include gnome-disk-utility so I'm fairly certain this isn't your bug. The alternate installer is provided by the package debian-installer and it would be more appropriate for you to file about about that package. Thanks!

Brian Murray, yes I know its about the gnome-disk-utility, and that is where I get the problem.

Whilst the alternative install doesn't have a GUI, what on earth has that to do with this error?

I was using the Disk Utility post install of the OS.

why not have the disk manager ask if you want to install it if you try to create a raid and dont have mdadm??
its confusing and makes it look broken.