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Thread: Fix for installing Kubuntu with a pre-existing RAID array in the system

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    Join Date
    Oct 2007
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    Aug 17th 2017
    Local Time
    03:42 AM

    Fix for installing Kubuntu with a pre-existing RAID array in the system

    My configuration boots off of an SSD with the root and swap partitions, and /home on a 2 GB RAID1 array. I suffered several failed installations with the installer not recognizing the pre-existing RAID array. I went through a number of failed attempts at repairing the system after the installation before I realized the source of the problem. Apparently, the Kubuntu installer does not support RAID arrays out of the box for clean installations. That possibility didn't even occur to me initially.

    The fix is fairly simple but a bit time consuming. Please read through the entire procedure before starting.

    1. Run the Live DVD all the way to the Plasma desktop. I think that the icon to get there is labeled "Try Kubuntu" or something like that. DO NOT install Kubuntu at this point.
    2. Open a terminal window and install mdadm by typing: sudo apt-get install mdadm
    3. Close the terminal and start the installation normally by double-clicking on the installation icon on the desktop
    4. Choose the manual partition mode, set your drive configurations appropriately. The RAID array will appear as a selection because mdadm is now installed. Without mdadm loaded prior to the installation, the RAID array will not be recognized and the system will either not install properly or even boot.
    5. The installer will reboot after installation, but will fail to load Kubuntu and will drop you at an "emergency recovery" text screen.
    This is actually a good thing.

    Some distributions drop users into a bash terminal, which would be useless in this situation.
    6. After entering your password on the emergency root console screen as prompted, type 'nano /ect/fstab' without the quotes.
    7. Comment out the RAID array line by adding a # sign in front of it.
    8. Save the results and reboot the system.
    9. Kubuntu will reboot and create a /home folder on the system drive. If for some reason it doesn't and goes into an infinite loop back to the login screen, change users on the login screen and log in as root
    10. Immediately open a terminal window and install mdadm by typing: sudo apt-get install mdadm
    11. Now restore fstab by editing it with 'sudo nano /etc/fstab' (without the quotes) and deleting the # sign you placed in front of the RAID's line earlier
    12. Save, exit the terminal window and reboot.
    System should boot properly with the RAID array as /home if that's your intended configuration
    13. Enjoy Kubuntu!

    I believe that this lack of RAID support on initial installation is a serious shortcoming of the installation process. mdadm should always by loaded by the system when RAID drives are detected as the Live DVD loads and analyzes the system. Proper RAID support is spotty amongst Linux distributions. OpenSUSE Tumbleweed properly detected and installed my RAID array during installation with no problems, but GeckoLinux based on OpenSUSE 42.2 did not. Not the desired performance if Linux aspires to achieve significant penetration into the desktop market.

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    Ascendant GreyGeek's Avatar
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    Feb 2009
    Lincoln, NE
    Local Date
    Aug 16th 2017
    Local Time
    10:42 PM

    Fix for installing Kubuntu with a pre-existing RAID array in the system

    Thanks for the heads up, Tanker Bob! That's good info to know. I'm running RAID1 on two 750Gb HDs, and have no plans to move away from KDE Neon User Edition on Btrfs, but I'll meet someone, sooner or later, who'll need that info!

    Sent from my iPhone using Tapatalk
    There is no truth in the news, and no news in the truth.

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    Ancient oshunluvr's Avatar
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    Feb 2010
    New Bern, NC USA
    Local Date
    Aug 16th 2017
    Local Time
    11:42 PM
    Yeah, if you're using mdadm raid it's not installed by default in any *buntu ISO that I'm aware if. Although I will state I haven't used mdadm since btrfs made it into the kernel. We all appreciate you taking the time to detail the issue you're having and it's resolution. In the past, I would boot to an ISO, "install" mdadm, then do the install. I was using a stand-alone boot partition in those days as well so that makes it much easier. I believe the presumption may be that if you're sufficiently proficient to run a RAID system, you can handle the extra complication of the process to get it working during installation.

    As far as your opinion about whether or not it mdadm should be included in the ISO, I would point out a couple things:

    #1 RAID use of any level is not common among most users.
    #2 ISO size is a constant battle (or has been in the past) so the developers must make a determination as to what should be included and what should be left out. Admittedly, as bandwidth and download limits increase and the transition from CD to DVD ROMs has happened, this is less and less important.
    #3 As always, it's up to the developers to decide what's what, not us.

    So if you think you can make the argument that mdadm should be a standard inclusion, then pitch your case to the development team. I can say as a regular visitor here, I don't recall seeing any posts about mdadm in maybe 4-5 years. As I have suggested, I doubt many users venture there often, and when they do, it's for a larger effort like a server, etc.

    Finally, I would like to suggest another solution to your issue - drop mdadm and/or hardware RAID altogether. Modern PCs with SATA, PCI-e, and M.2 interfaces, SSDs, and modern file systems like BTRFS (in the kernel) and ZFS (not in the kernel but install-able) almost entirely obviate the need for mdadm. I remember having 4 hard drives and having /var and other subdirectories mounted on different IDE channels to maximize throughput - but that was long ago in computer years. Now I luxuriously add or subtract drives and smoothly move from RAID0 to RAID1 and send entire installs from one drive to another - all without going off-line or rebooting. That's right - all that while still using the computer and without a reboot at the end. All these features and more at the hands of BTRFS. Food for thought.

    Be not the first by whom the new are tried, Nor yet the last to lay the old aside.
    Alexander Pope, An Essay on Criticism, 1711
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