====== Migrate data drives ======
This guide shows how to migrate data drives from an old server to a new machine. This works when the old server is still accessible. My setup is 2 HDD -> RAID 1 -> LVM2 -> LUKS -> ext4 so it is very important to do all the steps in the correct sequence as outlined below. In my setup all data is mounted as /home.

===== Old Server =====
==== File System ====
  - Unmount /home:<code>sudo umount /home</code>
  - You might need to force unmount. Alternatively, you may want to reboot the machine without LUKS to open the encrypted container.

update-initramfs -u
===== LUKS =====
  sudo cryptsetup luksHeaderBackup /dev/mapper/vg_data2-lv_home --header-backup-file /path/to/backup/header.img
  sudo cryptsetup luksErase /dev/sdb1
  sudo cryptsetup luksHeaderRestore /dev/sdb1 --header-backup-file /path/to/backup/header.img

https://superuser.com/questions/1596599/is-it-safe-to-move-a-luks-encrypted-partition-to-another-system-and-be-able-to-u
===== LVM2 =====
  - Make sure that no users are accessing files on the active volumes in the volume group, then unmount the logical volumes.
  - Use the -a n argument of the vgchange command to mark the volume group as inactive, which prevents any further activity on the volume group.
  - Use the vgexport command to export the volume group. This prevents it from being accessed by the system from which you are removing it.
  - pvscan
  - When the system is next shut down, you can unplug the disks that constitute the volume group and connect them to the new system.
  - When the disks are plugged into the new system, use the vgimport command to import the volume group, making it accessible to the new system.
  - Activate the volume group with the -a y argument of the vgchange command.
  - Mount the file system to make it available for use.

https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/4/html/cluster_logical_volume_manager/vg_move

  - Unmount filesystem(s): unmount /nfs (I also had an export mirror for a Samba share that I had to un-mount as well)
  - Deactivate logical volume(s): lvchange -an /dev/NASRaid1/NAS_LVM
  - Deactivate volume group: vgchange -an NASRaid1
  - Export the volume group: vgexport NASRaid1
  - Add RAID Array to new system and boot up. Running pvscan lists the exported volume group(s).
  - Import the volume group: vgimport NASRaid1
  - Activate the volume group: vgchange -ay NASRaid1
  - Activate the volume(s): lvchange -ay /dev/NASRaid1/NAS_LVM
  - Mount the filesystem(s): mkdir -p /nfs; mount /dev/NASRaid1/NAS_LVM /nfs

https://askubuntu.com/questions/529843/move-raid-1-array-to-new-system/529845#answers-header

===== RAID =====