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    SoftRAID, partitioning, boot loaders, mental

    I posted about a week ago asking about what I could expect the install to be like on my soon to arrive raid laptop ... Turns out its not good ...

    I think the point that I had been missing was the distinction between hardware (real) and software (fake) raid. Of course I got the latter (via tech vt8237).

    I made an initial attempt to follow https://help.ubuntu.com/community/FakeRaidHowto and set up fakeraid but that didnt go well at all so I thought Id settle for the builtin softraid solution (Im not clear on the advantages never mind the distinction between the two anyway) but thats not going well either.

    ---

    I run the install routine off the Alternate (AMD64 version) CD and get as far as the partitioner. I partition manually to set up softraid.

    On each of my two disks, I create the same partitions. For example I have tried 5G (with bootable flag), 0.5G, 94.5G, marking them all as "physical volume for raid". I then go up to "Configure software raid", where I bind the corresponding partitions on each disk into raid 0 multidisk configurations.

    This creates 3 new raid devices (10G, 1G, 189G). I set the 10G raid0 device to ext3 mounted as /, the 1G one as swap, and the 189G one as reiserfs mounted as /home.

    Installation continues until GRUB chokes:
    Unable to install GRUB in (hd0)
    Executing 'grub-install (hd0)' failed.
    This is a fatal error.
    hd0 ... hmmm .....

    LILO also chokes. It gives the option of installing on "/dev/md0: software RAID array" or "Other choice". md0 sounds right to me ...
    LILO installation failed
    Running "/sbin/lilo" failed with error code "1".
    I can still finish off the installation but I dont know how to boot in then, much less what I would need to change to get the loader to work if I could get in!

    What do I need to do? On one installation run I tried creating a /boot partition (at the start of the first disk) that was not part of a raid0 device - I figured that the boot loaders just didnt like being striped across disks. In this case the installation completed without trouble but then GRUB just hung during boot.

    Id love to hear from someone who has achieved this setup and would walk me through it.

    Thanks,
    a_l_a_n.

    #2
    Re: SoftRAID, partitioning, boot loaders, mental

    Ah, okay, Ive hit ALT-F2 after the failed boot loader steps and run liloconfig which informs me that
    Only RAID1 devices are supported as boot devices.

    Comment


      #3
      Re: SoftRAID, partitioning, boot loaders, mental

      http://forums.gentoo.org/viewtopic.php?p=2053048 suggests the following:

      grub> root (hd0,0)
      grub> setup (hd0)
      grub> root (hd1,0)
      grub> setup (hd1)
      grub> quit
      The second command spits out:
      Checking if "/boot/grub/stage1" exists... no
      Checking if "/grub/stage1" exists... no
      Error 15: File not found
      But an ls indicates that /boot/grub/stage1 does exist.

      Comment


        #4
        Re: SoftRAID, partitioning, boot loaders, mental

        Ah yes, and apparently GRUB cant read RAID0 either ... although I thought I read it could ...

        So this leaves me back with having to define a non-raid partition for boot, but like I said, thats already failed (hung GRUB).

        Comment


          #5
          Re: SoftRAID, partitioning, boot loaders, mental

          Got it! ... Or at least I got something.

          Had to disable RAID in the bios. Then, partitioning into a bootable RAID1 ext3 /boot, RAID0 /swap, and RAID0 reiserfs /, Kubuntu installed and booted normally.

          Perhaps this is the difference between Kubuntus builtin software RAID support and fakeraid ... that the latter utilises the bios

          Confusing subject ... Would still like to hear from people who understand this stuff.

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