ceph-disk zap in ruby

def zap(dev)
  # try to wipe out any GPT partition table backups.
  # sgdisk isn't too thorough.
  lba_size = 4096
  size = 33 * lba_size
  begin
    dev_file = open(dev, 'wb'):
    dev_file.seek(-size, IO::SEEK_END)
    dev_file.write("\0" * size)
  ensure
    dev_file.close
  end

  `sgdisk --zap-all --clear --mbrtogpt -- #{dev}`
end