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This page describes how to install Debian using the Serial ATA RAID (aka fake RAID, BIOS RAID) feature provided by your SATA disk controller. These are controllers that advertise RAID functions but are not supported by a hardware chip for parity.

Not to be confused with the Linux kernel's software RAID feature (Multidisk Device). This is the preferable and more reliable method to establish software RAID arrays.

See the Debian installation guide for more information.

Use the following method only if you want to have a dual-boot system with Debian and the other operating system on the same Serial ATA RAID:

  1. Set up your fake RAID in the BIOS (see owners manual).
  2. Boot from a Debian installation media.

  3. Move the cursor to the Install boot menu entry (do not hit Enter yet):

    1. Press Tab to edit the kernel boot line.

    2. Add dmraid=true to the end of the line.

    3. Press Enter.

      Note: In UEFI-installer you must press e key instead Tab and use arrow keys for moving to end of 4-st line (example for x86_64 architecture):

      • linux /install.amd/vmlinuz video=vesa:ywrap,mtrr vga=788 \ -- quiet

      Add dmraid=true to end of this line and press F10 or Ctrl+X to run installer.

      • linux /install.amd/vmlinuz video=vesa:ywrap,mtrr vga=788 \ -- quiet dmraid=true

  4. Install Debian as usual, until you get to the disk partitioner. You will see your fake RAID as one disk with a confusing long name. Use it as if it were a single disk and configure your partitions any way you want, including LVM and friends.
  5. Complete the installation. The installation of GRUB may fail, but that is OK; GRUB needs to be reinstalled either way. If GRUB installation fails, select "continue without bootloader" to complete the Debian installation.
  6. Reboot as instructed by Debian Installer.
  7. Boot using the Debian installation media again.
  8. In the boot menu, go to Advanced Options, and move the cursor to "Rescue system" (do not hit Enter yet):

    1. Press Tab to edit the kernel boot line.

    2. Add "dmraid=true" without quotes to the end of the line.
    3. Press Enter.

  9. You will be presented with screens similar to the installation screens. Go through with them until you are asked to choose a root filesystem to mount and use.
  10. Choose the first /dev/dm-? (? is a number). You will get a command prompt.
  11. (Optional) Type bash into the prompt, for easier command line editing and command history.

  12. Modify /etc/default/grub (e.g. nano /etc/default/grub) and uncomment GRUB_DISABLE_LINUX_UUID=true (699437). Save the file and exit the editor.

  13. Type update-grub and press enter. This is very important, because otherwise the GRUB boot menu later wont be able to display your freshly installed kernel!

  14. Type grub-install /dev/mapper/ and press tab and tab again, you will get the names of the fake raid partitions.

    1. Complete grub-install /dev/mapper/ with the name of your whole fake disk.

      For example grub-install /dev/mapper/isw-jggdha7s-SYS (Note that there is no number at the end of the name). You may have something like /dev/mapper/isw-jggdha7s-SYS and /dev/mapper/isw-jggdha7s-SYS1, or /dev/mapper/isw-jggdha7s-Volume and /dev/mapper/isw-jggdha7s-Volume1. Choose the one without the partition number and press enter.

    2. Everything should install now without an error.
  15. Type blkid | grep swap with the result of the command change the entry in the /etc/fstab. (e.g. nano /etc/fstab)

    1. Ex: /dev/mapper/isw.. to UUID="f7d88.." on the swap line
  16. Type exit (twice if you did step 11). Now you should be back in the rescue system menu. Choose the Reboot system option. Now boot off your fake RAID and see GRUB starting your new Debian installation.

Troubleshooting / Alternatives (mdadm)

An alternative for dmraid is mdadm. For that, install the package mdadm and set mdadm=true as kernel parameter in your grub configuration (GRUB_CMDLINE_LINUX_DEFAULT="quiet mdadm=true" in /etc/default/grub). Run update-grub after making the changes and amend /etc/fstab to match the new devices such as e.g. /dev/dm126p9, boot into Rescue Mode, investigate and amend this paragraph as you go along, please.

Alternative instructions

(Works with my Intel RST fakeraid in UEFI mode)

  1. Setup raid devices in BIOS
  2. Boot debian-installer with mdadm=true
  3. After detecting hardware and before starting the partitioner, ensure efivarfs is mounted; then run: mdadm --assemble --scan. It should detect your raid devices, they should show in /proc/mdstat.
  4. Partition disks, install system, etc., but don't finish the installation yet.
  5. See for fixes required in initramfs.

  6. Debian should now be able to boot from the fakeraid disk.

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