That brings us to the next alternative: an externally-attached disk. This definitely gets around the issue of data being stuck on a disk inside the machine. However, the external disk is still tethered to a single machine. It is possible to share folders within the disk across the network, allowing other machines to use the external disk as additional off-machine storage, but I often find Microsoft networking is maddeningly inconsistent. Despite following all the recommended practices, remote folders appear and disappear in what appears to be a rather random fashion, making this solution unreliable. Furthermore, if you do want to use this external storage arrangement to back up machines, you have to set up the backup processes yourself. Some external drives do come with backup software and an easy-to-administer mechanism, but they carry a price premium compared to the bare external drives—more of a premium than (to my mind) can be warranted by including a modestly-featured backup product along with a basic external drive.

So, here's a common situation: multiple machines, islands of data, no backup. The backup problem can be solved through the use of one of the online backup services like Mozy or countless other offerings. One problem with applying this solution to the situation: the backup offerings charge a monthly fee per machine—even at $5/month, six or seven machines can add up to a decent-sized tab. And then you're faced with trying to keep all of the separate backup accounts straight, not to mention trying to keep track of what data is in which backup account. You've taken an N-problem and converted it to an N-squared one. Not very attractive.

The answer for your home data center problem is obvious: you need a single storage device that each machine, whether Windows, Mac, or Linux, can use. In short, you need NAS. This solves the islands of storage problem. It also solves the not-every-platform problem. But what to use for your home data center NAS?

You can build your own. There are a bunch of Linux-based open source offerings around. But that makes you a Linux system administrator, probably not what you wanted. You want something simple.

Major vendors provide NAS devices, often called something else. HP, for example, just announced the MediaSmart Server, a product that provides centralized storage and helps with another aspect of today's home data center: sharing media among computers and other media devices (e.g., your TV). However, this product is based on Windows, giving you yet another Windows machine to manage, one with all of your important data, to boot. I'm not sure that's where I want to go.