by John B. Carnett: John B. Carnett

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Build a monster server in four steps

Cost: $850
Time: 2
Hour
Easy | | | | |Hard
Your whole life is on a hard drive: music, e-mail, family photos, tax returns. If that drive dies, then what?

Businesses that need to keep their data safe use a RAID (Redundant Array of Independent Disks) server, a stack of connected hard drives that functions as one disk. The servers simultaneously write multiple copies of data, so if one drive fails, nothing is lost. Retail home-RAID arrays start at around $700 for 750 gigabytes, but if you´ve got an unused desktop computer lying around (or want to pick one up on eBay), it´s easy to build your own RAID with as much storage as you want.

There are four main types of RAID, each of which makes tradeoffs between total storage size and redundancy. I used a RAID 5 array, which gave me 1.2 terabytes of storage from five 300-gigabyte disks. At that size, I saved about $550 over an off-the-shelf version. Just plug the drives into a RAID controller, a card that slips into an expansion slot inside your computer, and you´re done. Your Mac, PC or Linux operating system will treat the RAID as a single disk.

The machine plugs into your home network, so you can save to it-and pull file off it-from any computer in the house. And you can upgrade it with bigger drives down the road so that your digital safehouse never runs out of room.