cat /proc/mdstat

Discussion in 'Technical' started by mosaw, Feb 24, 2016.

  1. mosaw

    mosaw New Member

    Please help, I have the following output, does this show two failed drives in a 2 drive mdadm raid?

    # cat /proc/mdstat
    Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] [multipath] [faulty]
    md1 : active raid1 sdb1[1] sda1[2](F)
    20478912 blocks [2/1] [_U]
    md2 : active raid1 sdb2[1] sda2[2](F)
    955754432 blocks [2/1] [_U]
    unused devices: <none>
  2. Well-Known Member HowtoForge Supporter

    no, one drive failed - md1 and md2 are partitions.
  3. mosaw

    mosaw New Member

    thanks for the insight, I can remove sda from the array and disable raid for quick fix, is that correct?
  4. Well-Known Member HowtoForge Supporter

    No need to disable raid.
    I assume sda is the one which failed, please make really sure that's the case at your setup before doing anything, else you would need to adjust the commands

    1. Check your Raid
    mdadm --detail /dev/md1
    mdadm --detail /dev/md2
    2. Remove failed HDD from Array
    mdadm /dev/md1 -r /dev/sda1
    mdadm /dev/md2 -r /dev/sda2
    Just in case it won't let you remove the faulty drive, you can set it faulty using
    mdadm --manage /dev/md1 --fail /dev/sda1
    mdadm --manage /dev/md2 --fail /dev/sda2
    3. Wait for replacement of the faulty disk.

    4. With the new HDD in place begin repair

    If you are using GPT use this to prepare the new drive:
    # Copy GPT from sdb to sda
    sgdisk -R /dev/sda /dev/sdb
    # Create new UUID
    sgdisk -G /dev/sda
    If you are using MBR use this to prepare the new drive:
    # copy MBR from sdb to sda
    sfdisk -d /dev/sdb | sfdisk /dev/sda
    # reread partitions of sda
    sfdisk -R /dev/sda
    5. Let the new disk partitions rejoin your raid:
    mdadm /dev/md1 -a /dev/sda1
    mdadm /dev/md2 -a /dev/sda2
    6. Don't forget to reconfigure your boot-manager

    # if you booted the system
    grub-install /dev/sda
    Dont make me responsible if I did a mistake here or it doesn't work for you ;)
    Last edited: Feb 24, 2016
  5. mosaw

    mosaw New Member

    Thanks for taking the time to educate, I'm saved!
  6. misterm

    misterm Member HowtoForge Supporter

    We're totally eliminating the raid?

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