Multiple Device RAID5 array dissapears with 1 drive fail ??

    Hi Team.

    PC-setup is 1 systemdrive + 4 SATA HDD, using "Multiple Devices" in a RAID5

    Using plugin "Multiple Devices" all updated.


    The array is synced and "Clean" /dev/md0

    Created + Mounted, BTRFS, created shares. All is good.


    Then i power the system down, removes 1 drive (removes SATA cable)

    Powering up the system.

    The entire array, is completly missing, like it never existed.

    It's not showing up as dev/mdo "Clean, degraded" just gone....


    Only when I reconnect the original drive again, the Array shows up.

    What am I missing here ? As far as I can read the Array should still be functioning, and I sould be able to use the "Recover" function to add a new drive and resync the array.


    See before and after screenshots.

  • macom

    Approved the thread.

    in the first screen shot you see "auto-read-only".

    That means, that the raid is not yet completely built and not yet ready to use.

    If you pull a disk in this state, the whole thing is gone...

    TerraMaster T6-423

    Qnap TS-853A

    Qnap TS-451+

    Qnap TS-259 Pro+

    Thank you for taking your time to reply. But I still have no win.

    I have wiped all disks, and started over.

    Created a new raid5, did the sync, and confirmed in mdstat the Array is active and OMV reports it as "Clean"

    Shutdown system, removes 1-drive, and boots up again.

    Same as before, the array is missing in OMV, and mdstat appears to register all my drives as (S)pare.


    Re-activating the harddrive, now causes the array to be "auto-read-only" in mdstat, but "Clean" in OMV......

    Pulling a drive when shutdown results in an "inactive" array on boot. To re-activate the array needs CLI commands:


    1. mdadm --stop /dev/md0

    2. mdadm --assemble /dev/md0 /dev/vdd /dev/vdc /dev/vdb  


    If you final array state is "auto-read-only" when issue the CLI command: mdadm --readwrite /dev/md0


    If "md raid" detects a failed drive while the system is running it should fault and remove the drive from the array. If you detect S.M.A.R.T errors on a disk in the array you can pre-emptively use the "remove" option to fault and remove the drive from the array. That's when you can expect the array to remain online in a "degraded" state.


    When you are ready to physically swap out and replace the bad drive, you would expect the array to still be online but degraded on re-boot and that's when you use the "recover" option to effectively add the new drive to the array which should then re-sync to a "clean" state.

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