Windows Home Server actually uses a duplication scheme that makes sure all your machine backups (and shared folders) are stored, in full, on more than one drive

Windows Home Server actually uses a duplication scheme that makes sure all your machine backups (and shared folders) are stored, in full, on more than one drive on the server. It behaves pretty much like one big drive and duplicates across all the drives as needed. It's pretty likely a consumer won't need more than this since that equates to three copies of your data at any given time (laptop, server disk B, and server disk C).