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+# ZFS Metadata Eraser
+
+`erase-zfs-metadata.sh` permanently overwrites disk metadata that can identify
+a device as a ZFS vdev. It is intended for decommissioning or repurposing a
+device after it has been cleanly removed from its pool.
+
+## What It Erases
+
+The script performs 10 overwrite passes with zeroes over the first 4 MiB and
+the last 4 MiB of the target block device. These regions include:
+
+- MBR data and GPT primary partition table at the beginning of a disk.
+- GPT backup partition table at the end of a disk.
+- The four conventional ZFS vdev-label regions, including their redundant
+  copies at both ends of the device.
+
+It does not overwrite the entire device. Data outside those metadata regions
+may remain recoverable.
+
+## Requirements
+
+- Linux with Bash.
+- Root privileges.
+- `blockdev`, `dd`, `findmnt`, `lsblk`, and the ZFS `zpool` command.
+- A target device of at least 8 MiB that is not mounted and is not part of an
+  imported ZFS pool.
+
+## Use
+
+First, verify the target device carefully:
+
+```bash
+lsblk --output NAME,SIZE,TYPE,MOUNTPOINTS
+zpool status -P
+```
+
+Then make the script executable and run it with the full block-device path:
+
+```bash
+chmod +x erase-zfs-metadata.sh
+sudo ./erase-zfs-metadata.sh /dev/sdX
+```
+
+Replace `/dev/sdX` with the actual device, such as `/dev/sdb`,
+`/dev/nvme0n1`, or a device-mapper path. Do not use the disk containing the
+running system.
+
+The script displays target details and requires this exact confirmation before
+it writes anything:
+
+```text
+ERASE /dev/sdX
+```
+
+## Safety Behavior
+
+Before overwriting, the script refuses to run when:
+
+- The supplied path is not a block device.
+- The device itself is mounted.
+- A child partition of the device is mounted.
+- `zpool status -P` shows the device in an imported pool.
+- The device is smaller than 8 MiB.
+
+These checks reduce common mistakes but are not a substitute for verifying the
+device identity yourself. The operation is destructive and cannot be undone.
+
+## Prepare a ZFS Device
+
+For a device that belongs to a pool, first use the appropriate ZFS procedure,
+such as replacing or detaching the vdev, then export the pool if necessary.
+Confirm the target no longer appears in `zpool status -P` before running the
+eraser. Do not use this utility to remove a live vdev from an active pool.
+
+## Verify
+
+After completion, inspect the device for residual filesystem or partition
+signatures:
+
+```bash
+sudo wipefs --all --no-act /dev/sdX
+sudo zdb -l /dev/sdX
+```
+
+`wipefs --no-act` reports signatures without modifying the device. `zdb -l`
+should not find a readable ZFS label after a successful run.