Historically, our defense against a hard drive crash has been a complete disk image kept at a physically separate location - this image is copied back on to a replacement hard drive. This is the foundation of all Data Backup Software (MS Backup, Ghost, etc.) – the physical imaging of data.
But image-based backups have two major problems: they are very resource-hungry and they require a lot of manual intervention. So arduous is this that even disciplined IT shops do it as infrequently as is possible. Most small businesses and individuals seldom get around to doing backups.