Raid-1 installation & recovery start

How to start with raid-1, by musznik.

  • * You neeed separate ext2 /boot partition – easest way is to add pendrive or third disk with that mount point
  •  /boot partition should be on stable ground, connect hdd to sata-1 input! to prevent from disk name change after failure.
  1. create software raid druing debian installation
  2. create exactly same partitions on /dev/sdc1 and /dev/sdd2 (disk one and two)
  3. assign proper mount point to raid partitions (/ for /dev/md0, /var for /dev/md1 etc)
  4. create small partition for /boot on external drive (additional hdd or usb)
  5. assign grub to partition where is /boot
  6. thats is..

ok? but my one disk fail! how to start with one disk in raid-1 on debian?

  1. grub cannot start system, but it still able to load linux kernel (ufff) from external /boot partition
  2. you can run system on one disk using below procedure
    1. stop all md* devices
      mdadm --stop /dev/md*
    2. recreate raid-1
      mdadm --assemble --scan
    3. we need “mkconf” command from /usr folder
      1. ​find partition where is /usr
      2. mount that folder
        mkdir /tmp/help mount -t ext4 /dev/md0 /tmp/help
      3. backup current configuration and create new one
        mv /etc/mdadm/mdadm.conf /etc/mdadm/mdadm.conf.old /tmp/help/usr/share/mdadm/mkconf > /etc/mdadm/mdadm.conf
  3. prepare new disk
    1. create exactly same partition size as working hdd (you can use degradated disk with old data, which was removed for test?)
    2. using this command
      sfdisk -d /dev/sda > sfdisk /dev/sdb
    3. associate new hdd with raid-1
      mdadm --manage /dev/md0 --add /dev/sdb1 mdadm --manage /dev/md1 --add /dev/sdb5 mdadm --manage /dev/md2 --add /dev/sdb6
    4. and so one…
    5. watch rebuilding process
      watch -n 1 cat /proc/mdstat


There might be problem with SWAP partition. First stop whole swap (swapoff) or just restart system.

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