Answer Line: Can You Trust Important Data to CD-Rs?

Are CD-R discs a dependable medium for preserving digital photos, MP3s, and other key files?

Kenneth Collins, Hockessin, Delaware

Most CD-R manufacturers claim that their premium discs will last 100 years, if properly cared for. Mark Roosa, preservation director for the Library of Congress, is guardedly optimistic about the claim's accuracy. "If you put [a CD-R] into cool and dry storage, it's quite possible that it will last for 100 years." Here are some tips for keeping your CD-R data safe.

Buy good discs: Get premium CD-Rs from companies that make their own discs. (Don't use CD-RWs, since they aren't designed for long-term storage.) Katherine Cochrane, a consultant who specializes in CD technology, is impressed with some of the discs she has tested from Kodak, Mitsui, and Fuji. Other companies whose discs have good reputations include Verbatim and Maxell.

Check the newly written disc for errors: CDCheck, a free program from Fusion, lets you compare the CD's files to the original source files on your hard drive (see Figure 1). Find it at PCWorld.com's Downloads and at Fusion.

Make more than one copy: Put the same files on at least two CD-Rs. If the CD will be used a lot, make three copies--one for use and two for archiving.

Handle discs with care: Treat the disc as you would a photo negative. Never touch the data surface or lay the surface down.

Label with care: Use a pen designed for CD-Rs, such as CD Mark from TDK. Or use labels intended specifically for CDs--and apply them carefully. Better yet, follow Cochrane's advice: "Leave the disc unlabeled and just label the packaging."

Store them properly: Keep discs in their jewel cases when not in use, and store the case in a cool, dry, dark location. An office bookshelf (out of direct sunlight) should work fine. Be sure to store the second copy in another building.

Check them regularly: Every couple of years, pull the CDs off your shelf and make sure you can still read them. If you encounter an error, replace the disc with a new one duplicated from your other copy. (That's why you make two.) Consider obsolescence, too. If the medium or file format is falling out-of-date, transfer the data to a new storage device that's at least as reliable as the one it's replacing.