Backup an LVM logical volume via Rsync

lv_rsync_backup.sh

#!/bin/bash
# Backup an entire LVM logical volume via a snapshot LV and rsync

[[ $( whoami ) != 'root' ]] && echo "sudo please" && exit 1

set -o errexit
set -o nounset

# LVM logical volume to backup
lv=book01
# LVM Volume Group the LV belongs to
vg=/dev/shelf
# leave room for possible changes in original volume *while* backup is running
snap_size=1G
snap="$lv-snap"

snap_mnt_point=/mnt/$snap
stamp="$lv-$( date +%Y.%m.%d-%H.%M  )"

# backup destination, can be local/remote path that rsync recognizes
backup_dst=/var/shelf/book03/backups
log_file=$backup_dst/$stamp/backup.log

# limit the bandwidth used by rsync
rsync_bw=50M

main() {
  create_snapshot_lv
  backup
  cleanup
  echo "Alrighty! keep up the good work!" >&2
}

create_snapshot_lv() {
  echo "creating snapshot volume $snap with size: $snap_size" >&2
  lvcreate --size $snap_size --snapshot --name "$snap" "$vg/$lv"
  echo "mounting snapshot volume $snap to $snap_mnt_point" >&2
  mkdir -p $snap_mnt_point
  mount -o ro $vg/$snap $snap_mnt_point
}

backup() {
  num_files=$( rsync --archive --itemize-changes --dry-run "$snap_mnt_point/" 2>/dev/null | wc -l )
  mkdir -p "$backup_dst/$stamp"
  echo "dumping contents of $snap_mnt_point to $backup_dst/$stamp; total numer of files: $num_files" >&2
  count=0
  touch "$log_file"

  while read file; do
    echo $file >> $log_file
    count=$(( $count + 1 ))

    file_display="$( echo $file | cut -c1-100 )"
    count_display="[$count of $num_files files]"

    # \r for carriage return; and \e[K (equivalently \033[K) for clearing the line
    echo -ne "\r\e[K$count_display $file_display" >&2
  done < <( rsync --archive --verbose --bwlimit=$rsync_bw "$snap_mnt_point/" "$backup_dst/$stamp/" )
}

cleanup() {
  echo -e "\ncleaning up ..."
  umount -l "$snap_mnt_point"
  sleep 1s
  rmdir "$snap_mnt_point"
  # let lvremove prompt so you don't accidentally throw out an entire LV
  lvremove $vg/$snap
}

trap cleanup SIGINT SIGTERM
main