No, no, no MS!
Those suggesting a Linux alternative are missing the point - WHS was always meant to be something the average person with a bit of networking knowledge could implement, it wasn't meant to be a thing sysadmins could play with in their spare time. It was meant to be a set-up-and-forget solution offering not just NAS, but automatic backups of clients and a HD pool so you could simply add an extra (or replacement) drive and not have to reconfigure anything. It was about server-based home networking for the masses. OK, like many of MS's dreams it never achieved that, but the OS and the associated hardware was certainly up to the vision.
MS's ridiculous comments about larger HD becoming commonplace and therefore replacing the need from drive pools has, thankfully, now apparently been rescinded - lifted from Paul Thurrott:
The following quote from Microsoft’s Home and Small Business Server Team General Manager Kevin Kean:
Drive Extender was a neat feature, but the implementation was off, and we discovered some application compatibility and disk tool problems related to its ability to correct data errors on the fly. We don’t want to give customers problems; we want to give them solutions. So ultimately, we decided that we needed to cut out Drive Extender. Removing Drive Extender will make file shares easy, and it’s possible to accomplish most of its features otherwise. For example, you use the server’s centralized backup or even RAID as an alternative to data duplication.