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External Hard Drive for Backups

Based on notes posted by Thomas Stringer

Create an Encrypted Partition on an External Disk

Identify the external drive, using sudo fsarchiver probe simple or lsblk. Use fdisk to create a new partition if needed. Unmount the drive before proceeding as follows:

  1. Encrypt the partition with LUKS

    sudo cryptsetup luksFormat /dev/sda1

  2. Unlock the partition

    sudo cryptsetup luksOpen /dev/sda1 backup-disk

  3. Format the partition

    sudo mkfs.ext4 /dev/mapper/backup-disk

  4. Close the Encrypted Disk

    sudo cryptsetup luksClose backup-disk

You can now the use external drive to perform backups to the encrypted partition. Try rsync -av.

Erase a Disk

Fastest way is to use sudo wipefs -a /dev/sdX. However, data can still be recovered from the disk. A more secure approach is to overwrite the entire disk with zeros: sudo dd if=/dev/zero of=/dev/sdX bs=4M status=progress. For USB flash drives and SD Cards use a block size of 1M or 2M so as not to overload the controller. A block size of 16M would probably work well with an NVMe drive.