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Thread: Bootloader on both harddrives raid 1.

  1. #1
    Join Date
    Jul 2008
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    Maastricht
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    Bootloader on both harddrives raid 1.

    Not really Directadmin but maybe I still can get some help.

    I want to replace a harddisk (/dev/sdb) in a raid 1 system on Centos 6.9.

    At this moment the system is booting from this drive, I'm sure about that. Booting from /dev/sda will result in no booting due to a missing bootloader.

    The drive /dev/sdb/ is now in the system, but not in the raid 1 anymore. I removed it with mdadm.
    I gave the command:
    Code:
    grub-install /dev/sda
    which is my first harddisk in fact and which is still in raid mode.

    Will this be enough to boot from /dev/sda when I remove /dev/sdb from the system?

    Or do I need to manually do some grub commands? How can I test to be sure the bootloader is on both drives and will automatically boot one drive if the other is not present?
    I want to replace the drive and would not like to end up with a non booting system.
    Greetings, Richard.

  2. #2
    Join Date
    May 2008
    Posts
    556
    I cannot directly answer your question but I can share my experience with a Dell server. We got a raid1 array with two 160GB drives and we wanted to upgrade it to 320GB. I stopped the server, changed one of the disks and booted it. The bios fount that the array needs a rebuild and I just waited it to be done. Then I shut it off again and changed the other disk. Same rebuilt procedure and everything was live and working.

    So I guess you can simply test it the way I did. Unplug one of the drives and see what happens

  3. #3
    Join Date
    Jul 2008
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    Maastricht
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    That would be possible if I had physical access to the drives, which isn't the case, they are in Germany.
    I don't use the bios either for raid, because if you need to change mainbord for some reason, and you can't replace it with the same, you're stuck.
    So I rather use software raid or hardware raid (by raid controller).

    Thank you for your answer anyway, appreciate it!
    Greetings, Richard.

  4. #4
    Join Date
    Jul 2008
    Location
    Maastricht
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    3,119
    For future references... I found some "dd" commands to investigate, glad I did not run them. DD says "disk destroy" to me so always be carefull.
    However I found a tool named Bootinfoscript on Sourceforge, which gives lots of info about hard drive partitions, raid and where bootloaders and grub (and some others) are.
    According to this tool I got bootloaders on both harddisks, so thumbs up.
    Greetings, Richard.

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