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As more and more of your life’s records and memories are stored in digital form, it makes sense to explore the best ways to keep them secure. All methods have drawbacks, some of them glaring. Floppy disks are all but dead as a format. ZIP disks are expensive for their capacity. CD/DVD backups are great—if you remember to make them. A lone hard disk will fail, sooner or later.

What’s left? Backing up to another hard drive, either an external disk or one on a dedicated PC. In my June 22 PC Magazine column, I discussed the former option. Here we will tackle refurbishing an older PC for use as a backup data server (a computer devoted to storing backups from all your other computers).

As many users get new PCs every two to five years, it’s likely that you have an older PC around that’s available for duty. This may be your most cost-effective backup solution. We will steer a course midway between doing the job inexpensively and ensuring that a hardware failure is unlikely. Bear in mind that you can get a whole new PC for $400.

Any Pentium III, and probably Pentium II, PC should be fast enough for our purposes. PCs built since 2000 have the best chance of being converted to run Windows XP. Nearly all consumer PCs since fall 2001 come with Windows XP, which saves you the cost of upgrading. If the PC was built before 2000, it’s probably not worth the effort. If you don’t know its age, stick with Pentium III, Athlon, or newer models. Computers less than five years old probably have enough life left in their mechanical components to be worth reusing.

If your server-in-waiting has been in storage, boot it up before making any enhancements. (First, shake it gently to make sure there are no loose screws inside that could cause a short circuit.) If it doesn’t boot, check for the obvious—an unseated CPU or memory card (check with the power line unplugged) or a bad power connection—and decide how much you’re willing to tinker with the system. Many computer stores have a minimum shop rate of $100.

The cost of components can quickly add up, so shop around for the best prices. Make this a month-long project, and you’ll find most of what you want on sale. Sites such as Techbargains.com can help direct you. The items you’re most likely to need—hard drive, memory, network card—are among those most often on sale.

Nearly every PC has room for two hard drives; consider keeping the existing one to handle the OS, and store backup files only on the new drive. With hard drives so affordable, you should buy more capacity than you need. A huge hard disk will let you keep a complete image of your PC (created by Norton Ghost or similar program) just in case. For the greatest savings, look for products marked “refurbished.”

For the most security, consider RAID, or redundant array of inexpensive drives. In this configuration, data is spread across two or more drives. To keep RAID affordable, you want RAID 1, where the same data is mirrored on each of two drives. The controller can be software or a hardware add-in card. Figure $200 to $500 for the controller and the pair of drives. You can buy either standard or serial ATA controllers (if SATA, make sure to buy power cable adapters). If you go with RAID, make sure the controller and drives work together, and verify OS support. Though RAID costs more than a standard hard drive, it may be one of the best places to spend your money, for if you don’t keep backups elsewhere, RAID will ensure that a single-disk failure doesn’t wipe you out.

You might need a network card. Consider gigabit Ethernet adapters if you think the server will still be functional by the time your other devices (and switch) are upgraded. If yours is a wireless house, add a wireless PCI card. Spend a little more for 802.11g. You might want add a USB 2.0 adapter card ($20) for direct transfers.

To get your PCs to see the new server, you’ll have to run the Windows network setup wizard from each PC. Go to Control Panel, choose Network and Internet Connections, then Set Up or Change Your Home or Small Office Network. Mostly, you can accept default prompts. If you have broadband Internet access and your PCs are linked through a switch and router, generally check “residential gateway” as your Internet connection method. Give the same workgroup name to all PCs (MSHOME is a Microsoft default; GATEWAY is common, too; if a broadband provider set it up, it may be, for example, COMCAST). If the machines aren’t all running Windows XP, you may need to create a setup disk to use on the others; otherwise, choose Just Finish the Wizard and go on to the next computer.

You’ll need to enable shared access to folders on the PCs being backed up. Go to My Computer, click on the folders you want backed up, and drag them to Shared Documents (in Other Places). You may want to map your drives or folders, making drives or folders on other PCs appear as if they’re one more local drive. If your backup method is to send files to the server, you’ll need to make the server a local drive on each PC you’re backing up. First, find the server in My Network Places, then find the drive you’re backing up to. Right-click on the drive and choose Map Network Drive, pick a drive letter (S for server is good), and check the Reconnect at Logon box. (You can also find a Linux server this way.)

If the server is pulling files from your PCs, do the same thing, but from the server: Find each PC to be backed up in My Network Places, then map the drives, but with a different letter for each PC. You can choose to make My Documents, rather than the whole C: drive, into a mapped drive.

Given the price of Windows XP, free Linux—say, Red Hat or Suse—is worth considering. Linux is definitely reliable. Make sure all your devices are supported, particularly wireless cards and drive controllers. Linux also offers free or low-cost backup utilities. It is easy to install; see our sister site, extremetech.com, and/or invite over a Linux-using friend.

While you can use Windows’ own backup utility with its limited across-the-LAN backup abilities (it will back up to mapped network drives), you may prefer third-party software, which can do the job better. Look for software that does versioning (multiple iterations of the same file). Dantz and NTI offer some products affordable for individuals For example, Dantz Retrospect Professional 6.5,($90 street)—a PC Magazine Editor’s Choice; see our Utility Guide (June 8, page 96)—works on three PCs, one of which can be a server, and lets you use a single PC to schedule backups for all PCs.

Once you’re up and running, figure out what you want backed up. By Windows convention, almost all your data files will be in My Documents, but you may have important files in c:\downloads, and you’ll want to back up your system registry. It’s possible to make incremental backups (of only the data that’s been changed since the last backup) and compressed backups, but once a week you might want to do a full, uncompressed copy, so you have a drive full of up-to-date data that most any PC can read. Don’t forget to maintain antivirus software on your new server.

For insurance, use another method to take backups offsite. Use a CD or DVD recorder to make a one-time full backup, then make weekly or monthly incremental backups. For your most valuable data, consider online backup (free to $50 a month).

An older PC can often be converted into a backup data server. Refurbishing costs, though, can quickly add up.Before proceeding, be sure to determine what needs updating, and whether it’s worth the price.