howto mount drives without loss of data (NOOB)

    • OMV 4.x
    • Resolved
    • Hi,
      to get rid of the ZFS signatures, run:

      (1)
      wipefs -b -o 0xe8e0d3f000 -t noext4 /dev/sdb
      wipefs -b -o 0xe8e0c3f000 -t noext4 /dev/sdb1

      (This will remove any signature BUT ext4 at the given offset on the given device)

      (2)
      After that run the following commands again:
      wipefs -n /dev/sdb
      wipefs -n /dev/sdb1

      If there are still ZFS signatures displayed, run the following commands

      wipefs -b -o <newly-found-offset> -t noext4 /dev/sdb

      wipefs -b -o <newly-found-offset> -t noext4 /dev/sdb1

      Continue with (2) until there are no more ZFS signatures displayed.
      I needed 15 runs of "wipefs -b -o ..." (probably because I was playing around with ZFS before going for mdadm/ext4)

      Good luck,
      Thomas
    • Yes, succes!!

      Did exactly as you all suggested.

      to see the zfs signatures to delete:
      wipefs -n /dev/sdb

      Then to delete them
      wipefs -b -o 0xe8e0d3f000 -t noext4 /dev/sdb

      In my case, there were only zfs signatures on the sdb drive, not on any sdb1...
      after that rebooted into OMV 4.x and the drive is there again. And most important, all data is there and still in one piece. !!!


      Thank you @geaves, thank you @ananas and thank you @tkaiser
    • geaves wrote:

      edterbak wrote:

      does NOT work in OMV,
      You didn't have to do that :) OMV-Extras Kernel tab scroll to the bottom, install from there and then use the reboot button....but that's OK you now have a rescue usb for next time ;)
      No, I didnt. Missed that.
      However, I called the wipefs command. It is there and it reacts as it should. Although, when it tells me the ZFS signature is deleted, it is not. Just as mentioned in other threads.
      I would gues (as a noob) that if a command responds, it can be used and it is functional. But I might be wrong :)

      Anyway. You are right. I got it working thanks to your help. THANKS!!!
    • In Debian Stretch (OMV4) the version of util-linux (including wipefs) is 2.29.2-1+deb9u1.

      Current stable version of util-linux is 2.32.1. In Debian this version is in the testing repo and has the following note for wipefs:

      Note that some filesystems and some partition tables store more magic strings on the device (e.g. FAT, ZFS, GPT). The wipefs command (since v2.31) lists all the offset where a magic strings have been detected.

      So new version with additional functionality.

      Debian is quite conservative when it comes to updates, so when you need newer versions then the ones that are in the repo you need some kind of work around. ;)
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