LTO-Restore.sh

gistfile1.txt

#!/usr/bin/env bash
#Copyright 2026 fennectech
#
# Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
#
# 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
#
# 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

echo "THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
set -euo pipefail
TAPE_DEVICE="/dev/nst0"
FIFO="/tmp/btrfs_restore_fifo_$$"
[[ $# -ne 1 ]] && { echo "Usage: $0 /path/to/mountpoint"; exit 1; }
DESTINATION="$1"
RECV_PID=""
cleanup() {
    if [[ -n "$RECV_PID" ]] && kill -0 "$RECV_PID" 2>/dev/null; then
        kill "$RECV_PID" 2>/dev/null
        wait "$RECV_PID" 2>/dev/null || true
    fi
    exec 3>&- 2>/dev/null || true
    rm -f "$FIFO"
}
trap cleanup EXIT
mkfifo "$FIFO"
btrfs receive "$DESTINATION" < "$FIFO" &
RECV_PID=$!
exec 3>"$FIFO"
wait_for_drive_ready() {
    local attempts=0
    local max_attempts=60
    echo "Waiting for drive to become ready..."
    until mt -f "$TAPE_DEVICE" status &>/dev/null; do
        sleep 2
        (( attempts++ ))
        if (( attempts >= max_attempts )); then
            echo "ERROR: Tape drive did not become ready after $(( max_attempts * 2 )) seconds."
            exit 1
        fi
    done
    echo "Drive is ready."
}
wait_for_rewind() {
    local attempts=0
    local max_attempts=120
    echo "Waiting for rewind to complete..."
    until mt -f "$TAPE_DEVICE" status 2>&1 | grep -q "File number=0, block number=0"; do
        sleep 1
        (( attempts++ ))
        if (( attempts >= max_attempts )); then
            echo "ERROR: Rewind did not complete after ${max_attempts} seconds."
            exit 1
        fi
    done
    echo "Rewind complete."
}
TAPE_NUM=1
while kill -0 "$RECV_PID" 2>/dev/null; do
    echo "Insert tape #${TAPE_NUM} and press ENTER when the drive load light is solid (or Ctrl+C to abort)..."
    read -r < /dev/tty
    wait_for_drive_ready
    echo "Rewinding tape #${TAPE_NUM}..."
    if ! mt -f "$TAPE_DEVICE" rewind; then
        echo "ERROR: Rewind command failed on tape #${TAPE_NUM}."
        exit 1
    fi
    wait_for_rewind
    echo "Setting variable block mode on tape #${TAPE_NUM}..."
    if ! mt -f "$TAPE_DEVICE" setblk 0; then
        echo "ERROR: Failed to set variable block mode on tape #${TAPE_NUM}."
        exit 1
    fi
    echo "Reading tape #${TAPE_NUM}..."
    if ! dd if="$TAPE_DEVICE" bs=1024k status=progress >&3; then
        echo "ERROR: Failed reading tape #${TAPE_NUM} — aborting."
        exit 1
    fi
    echo "Tape #${TAPE_NUM} done. Ejecting..."
    mt -f "$TAPE_DEVICE" eject || echo "WARNING: Eject failed — please remove tape #${TAPE_NUM} manually."
    echo "You may remove tape #${TAPE_NUM}."
    (( TAPE_NUM++ ))
done
exec 3>&-
if ! wait "$RECV_PID"; then
    echo "ERROR: btrfs receive failed — restore may be incomplete or corrupt."
    exit 1
fi
echo "Restore complete."