THE hard disk has crashed and you have had to re-format it. You are halfway through restoring the files from your back-up diskettes when you get the dreaded message: ''Data Error Reading Drive A''. No problem. You pull out the second back-up set and start again. When you get the same message from the second set, and the drive head cleaning kit makes no difference, you wish you had spent the money and bought a tape back-up, even though your hard disk is a modest little 80 MB dinosaur you bought in 1992. After pounding the keyboard, kicking the CPU and weeping with frustration, you can consider rewriting the material or going to one of the specialist data recovery firms who will, for a fat fee, weave some magic and get your files back. There is a cheaper way, though, provided by the Polaroid Corporation, which has been in the thin-film magnetic media business for 35 years. Polaroid makes the usual range of diskettes but also offers a special range called DataRescue Diskettes. DataRescue diskettes are a little more expensive but with each box comes a 20-year warranty and, in the event of an unreadable diskette, a cast-iron offer to ''make every attempt to recover 100 per cent of your data free of charge . . . within 48 hours''. I've been using the DataRescue diskettes for three years and had no occasion to use the service until recently, when a file back-up and a second back-up failed. Both were 3.5-inch HD diskettes, holding about 200 news story files, and I tried to recover one of them with Norton software. After several hours, I found myself with a pitifully small collection of files, none of which were the ones I wanted. When Norton produced an identical diagnosis for the second diskette, I decided not to risk it and sent the diskette by airmail to the Polaroid DataRescue Service in Santa Rosa, California. The system really works. One small, unimportant file, out of 200 or so, was irretrievable. Polaroid recovered almost all the rest intact. Ten files, reported by Polaroid as ''slightly damaged'', were rejected by the word processor software but were recovered by reading them as ASCII files, removing the format information and re-importing, which took about 15 minutes. With the recovered diskette came a comprehensive report, signed by a Polaroid engineer. This noted the presence of mildew but stated that the failure had been due solely to ''a deep radial scratch''. The damaged files were all identified by the original file names. The process took just over two weeks, from sending the diskette to picking up the replacement, with a free back-up copy, from the Polaroid office in Causeway Bay. A courier would have been much faster because Polaroid always returns disks by the same method as that used by the sender. It is difficult to put a value on a file, particularly when the writer's original source material has been scrapped. Many will see the few dollars extra one pays for the DataRescue service as a real bargain.
