I have 6 disks (2x 1tb and 4x 4tb) and want the following setup:

  • 2x 1tb disks in raid 1 (mounting point /)
  • 4x 4tb disks in raid 5 (mounting point /home)

I got the following messages:

If you put all disks into RAIDs or LVM VGs, there will be nowhere to put the boot partition.


You must mount a partition of a local disk at /boot to continue.

help.ubuntu.com says:

Warning: the /boot filesystem cannot use any softRAID level other than 1 with the stock Ubuntu bootloader. If you want to use some other RAID level for most things, you'll need to create separate partitions and make a RAID1 device for /boot.

I also tried to split the raid 1 in two raid 1, one to mount as / and one to mount as /boot, but i am not able to select /boot as mounting point for the second array (greyed out).

What did i forgot?


I switched to the Ubuntu 18.04.1 LTS alternate server image. Here it works!


Use an usb stick for /boot ext4 😁 bypassing your problem Any of the drive fails you will still boot from the usb stick and will work the degraded drive.

  • This is a smart solution. I always have a non-raid drive boot drive for simplicity. – user535733 Dec 16 '18 at 0:22

Seems to be a bug in the new installer: https://bugs.launchpad.net/subiquity/+bug/1785332

Downloading the alternative installer seems to fix it:


Make sure the *.iso file name does not contain "live" in the file name if you want to use the alternative server image.

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