The University of Pennsylvania's Online Computing Magazine
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March 1993 - Volume 9:5 [Printout | Contents | Search ]
By Tom Gudmundsen and Edda Katz Someday the internal hard disk of your PC or Macintosh will fail-- it's not a question of "if" but of "when." The consequences of a disk failure are unpredictable. In some instances, you'll be able to restart your drive relatively easily and suffer little or no data loss. In more severe cases, you'll have to spend much time and effort reconstructing the contents of your hard disk. And in the most severe cases, both your drive and the data on it will be irrecoverable. Keeping your system fully backed up at all times is, of course, the best defense against potential data loss and the attendant anxiety. The information here is intended to help you diagnose the cause of a disk failure and offer some suggestions for recovering your disk and its contents. Some familiarity with your computer and its operating system is assumed. If the procedures described here fail to recover your disk, we recommend that you consult a service technician at an authorized computer repair service.
Viruses and disk failureA computer virus can cause symptoms similar to those that signal a disk failure. For example, on a PC you may see an error message, and a Macintosh may "hang" after it starts to boot. If you don't have antiviral software installed on your system and have used floppy disks that could have carried a virus from an infected computer, check your system for viruses. Vi-Spy 10.0 for IBM PC/compatible systems and Disinfectant 3.0 for Macintoshes can be obtained at the Computing Resource Center at no charge. Use the software to look for and eradicate any viruses that may be present.
IBM PC/compatible systemsAssuming your system is virus free, you'll know your hard disk has failed if you see one of several possible error messages on your screen. Some of the most common ones are
If you suspect a hardware problem, the first step is to take your PC to a computer repair service for further checking. If testing confirms that the drive is damaged, you have the choice of replacing the drive (and losing all the data on it) or sending the drive to a data recovery service. Service technicians there will dismantle the drive in a "clean room," put its platters into an identical drive, and try to restore the data to a new hard drive. Recovery services are, however, very expensive--whether or not you use one depends on how valuable your data is (see sidebar on page 16). If you can see the C: prompt, the system files may need to be replaced. Damaged system files are a common cause of disk failure. Start by copying all the data files for which you don't have backup copies to floppy disks. This is a precaution in case your hard disk cannot be revived. Don't bother copying application files--you'll need to reinstall them from originals if you recover your drive. While copying files, you may get one or both of the following error messages:
Next, replace the DOS system files on your hard drive. At the A: prompt, type sys C:. You'll see the message "system transferred" when the system files have been transferred from the floppy disk to the hard disk. Also copy the command.com file to the hard drive. Then try to reboot your machine without the floppy DOS disk in drive A. If it works, you should still have your system checked out at a repair service. Once you've had your system checked out, you can start to restore files from any backups you have and/or recover any damaged files you weren't able to copy to floppies earlier. There are several commercial file recovery utilities on the market for this purpose. Norton Utilities, which is very easy to use, is the one with which the CRC has had the greatest success. PCTools, a utility similar to Norton, is also very popular. In general, ascii (text) files are easier to recover than formatted files, and spreadsheet files are the most difficult to recover. If your system didn't reboot without the floppy DOS diskette, you may need to reformat the hard drive. Subsequent recovery attempts will then be more time-consuming. Before taking this step, the CRC recommends you have a service technician evaluate your system.
MacintoshesWhen a Macintosh hard disk fails, a question mark or "sad Mac" will appear on the screen, or your system will start to boot but "hang." As with a PC, the failure may be hardware- or software-based. To determine which it is, boot your machine from a floppy system diskette and look for the hard disk icon. Use the System Tools disk if you are running System 6.x, and use the Disk Tools disk if you are running System 7.x.If you can see the hard disk icon, you probably have a software failure. As on a PC, damaged system files are frequently the culprit, so reinstalling them is the first thing to try. Before you start, copy all data files for which you don't have backups to floppies. This is a precaution in case attempts to restart the hard disk don't work or do further damage to the data or the drive. Attempts to copy damaged files will produce the message "error reading file" followed by the file name. Note the names of these files--you can try to recover them once your system is up and running again. The next step is to remove the old System folder by throwing it into the trash can and emptying it. Then reinstall the system software to the hard drive and restart your computer to see if it will boot from the hard drive. If it does reboot with the newly installed system software, you're back in business. You will, however, still need to reinstall any applications that don't work correctly and restore any damaged files using one of the utility programs mentioned below. Also have your system checked out by an authorized Apple dealer. If your system doesn't reboot, don't despair--you still have a few cards to play. There are numerous utilities you can use to repair your disk and restore data. Disk First Aid, which is provided with the system software, is the first one to try. The CRC's favorite utility is Norton Utilities for the Macintosh, which is easy to use and effective. MacTools, another popular utility, is also easy to use. Note that all these utilities require System software version 6 or higher. If you didn't see the hard disk icon when you booted from Disk Tools or System Tools diskette, you need to check for hardware damage. For an Apple-brand hard disk, run the HD SC Setup utility. You'll find it on the Disk Tools disk if you're running System 7.x and on the Utilities 1 disk if you're running System 6.x (you need to first eject the System Tools disk and insert the Utilities 1 disk). For a non-Apple drive, insert the setup disk supplied with the drive; under no circumstances should you use the Apple HD SC Setup utility with a non- Apple drive. If you see the message "no valid drive available," you have a hardware failure. For a second opinion, have the drive checked out at a repair service. If testing confirms that the drive is damaged, the only way to recover the data is to send it to an outside service, as described earlier. If you don't see the message, there's a possibility that the software that operates your hard drive has been corrupted. To check out that possibility, click on the "update SCSI driver" option that you'll see on the screen. Do not select any of the other options (Test, Initialize, or Format). Then restart to see if you can boot from the hard drive. If you can, you're home free. If you still can't boot from the hard drive, have the system evaluated at an authorized Apple repair depot.
Staying out of troubleFollow these steps to minimize the effects of a disk failure and protect your system:
Sidebar 1: Computer repair services Listed below are the four external repair services the University recommends. In addition, the service department of the Computer Connection is an authorized repair center for IBM PS/2 and Apple Macintosh systems. The University's Purchasing Department advises users to get cost and response-time estimates before authorizing service.
Computer Fixer
IBM
System & Service Pros
Valens Business Machines
Sidebar 2: Data recovery services Listed below are three data recovery services you may wish to investigate on your own. The Computing Resource Center has not used these services, so no recommendation is implied. Their prices range from $75-$200 just to look at a drive, and from $10-$200 dollars per Mbyte of recovered information.
Drive Savers
DATA Rx
Ontrack Data Recovery
TOM GUDMUNDSEN is a Consultant, and EDDA KATZ is Information Manager, for the Computing Resource Center.
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