#!/bin/bash
# Wipes the ZFS labels off of a disk
# The metadata of zfs is stored in the first and last two 256kB of each disk involved in zfs.

DISK=$1

if [[ -z "$1" ]]; then
  echo "Usage: $0 <disk>"
  exit 1
fi

# List the labels
echo "-> About to clear these labels off of this disk: $DISK" 
blkid "$DISK"
lsblk --output NAME,FSTYPE,MODEL,LABEL,PTTYPE,SIZE -e 7 "$DISK"
echo "-> Are you sure you want to continue? (y/n)"
read input && if [ "$input" != "y" ]; then exit 1; fi

# Wipe all partitions and MBR and GPT labels
sudo sgdisk -Z "$DISK"

# Wipe the metadata off the front of the disk
sudo dd if=/dev/zero of="$DISK" bs=512k count=10

# Wipe the metadata off the back of the disk
sudo dd if=/dev/zero of="$DISK" bs=512k seek=$(( $(blockdev --getsz "$DISK") - 4096 )) count=1M

# List the labels
echo "-> Labels now on the disk"
blkid "$DISK"
lsblk --output NAME,FSTYPE,MODEL,LABEL,PTTYPE,SIZE -e 7 "$DISK"