Classic Computer Magazine Archive COMPUTE! ISSUE 128 / APRIL 1991 / PAGE 80

Don't be afraid to format your hard disk. (column)
by Tony Roberts

If you'd prefer having major dental work to doing battle with DOS's infamous FDISK, you're not alone. From time to time, however, hard disks must be reformatted, and the task is not a heinous one if you approach it logically.

First, there are two levels of formatting for hard disks - low and high. To understand the difference, first imagine an empty field that's the future site for a football field. This is the physical hard disk. Second, contractors are hired, the field is cleaned up and leveled off, and a beautiful stand of grass is planted. This is the low-level format. Finally, a grid work of white lines is laid on the grass to indicate field position, fair territory, out of bounds, and end zones. This is the high-level format.

Several times a season, the field is relined so that the game can be properly contained. Every few years, however, hard play will have broken down the field, and a low-level reformatting will be required. The sod must be torn up, fresh soil added, and the surface rebuilt.

Occasionally, when working with floppy disks, you'll find a disk that doesn't hold data. You reformat it, and if that doesn't solve the problem, you toss the disk out with yesterday's junk mail. Hard disks are another story, though.

Because of the expense involved, trashing a hard disk is not a palatable option, but a low-level reformat can often return a flaky hard disk to full productivity.

To format a hard disk from scratch, you must perform a low-level format, partition the disk with FDISK, and perform a high-level format (with /S if the hard disk is to be bootable). Obviously, reformatting a hard disk means that you'll wipe out all the data stored there. Make at least one full backup of your system, and have more than one copy of any irreplaceable programs or data.

To perform a low-level format, you'll need a special program, since DOS doesn't provide software to handle this chore. The setup disk that came with your system may have such a program. If not, you may need a commercial or shareware utility.

When you perform a low-level format, you're asked to enter information about any known bad tracks. This information is provided by the disk manufacturer and is often taped to the top of the hard drive.

If you don't have this bad-track information, you can perform a surface analysis to locate physical defects on the disk's surface and cordon them off. The surface analysis takes quite a while, but it gets the job done.

Next, proceed with the low-level format. When the low-level format is complete, reboot from a floppy containing the DOS version you want installed on the hard disk and run FDISK to set up your disk for use with DOS.

If you have a disk larger than 32 megabytes and you're using DOS 3.3. or lower, you'll have to partition your disk into two or more logical units. This is done with FDISK.

The first step is to create the DOS partition. Next, you'll add any extended DOS partitions. And finally, you'll need to assign drive letter names to the extended DOS partitions.

FDISK prompts you through this process. With DOS 4.01, the 32-megabyte barrier was eliminated so larger hard disks can be set up in a single partition.

Once FDISK has done its work the drive can be high-level formatted with the DOS FORMAT command, Each logical drive, or partition, is formatted separately.

Use FORMAT /S for the primary bootable partition and FORMAT for the others. Once the formatting is done, restore the data from your backups.

FDISK is a frightening command for many PC users because it can wipe out hard disks. But it shouldn't cause fearful reactions. After all, it's supposed to wipe out data. Just make sure everything is backed up properly before using FDISK to change the structure of your hard disks.

Many computer users first face FDISK when upgrading from DOS 3.3 to DOS 4.01 to take advantage of the feature allowing larger partitions. This process involves backing up each partition of the existing hard disk, rebooting from a floppy containing the new DOS, using FDISK to remove existing DOS partitions, using FDISK to create a new primary DOS partition, formatting the hard drive with FORMAT /S, installing the new DOS files on the hard disk, and restoring data from the backups, being careful not to overwrite the new DOS files with the old ones.

As in the case above, it isn't always necessary to perform a low-level reformat when changing the structure of a disk. If you question the disk's ability to hold data, though, I'd recommend it.

Hard disks have come down drastically in price in the last few years, and they are definitely becoming more common. In many systems, one hard disk isn't enough to handle today's huge programs and data files. These changes increase the likelihood that someday you'll be faced with reformatting a hard drive. There's nothing to fear; just back up your files, take your time, and work step by step.