Disk drives have moving parts. These parts include the rotating platters and the read/write heads that move back and forth over the platters. When a disk is first formatted, it starts placing the format down at the beginning of where the heads can write. (On most drives, this is usually the inner part of the disk drive toward the small hole in the platter.) When a disk drive is first formatted, it is new and the parts have not been used very much; hence they don't have much wear on them. As the drive is used, the read/write mechanism tends to start drifting away from the original format because it no longer lines up to the same starting point.
If the read/write heads drift too far away from the original format of the drive, they will no longer be able to read the information stored on the platters and will need to be reformatted. You need to reformat a disk drive when it can no longer read information that is stored on it.
When a disk drive is formatted, all of the data that was stored on it is lost. Because all your data will be lost, you may want to copy the data to another drive or to diskettes before reformatting the disk drive. For more information, refer to the tar, cpio, or restore commands.
You must have root user authority to execute this task.
1. Reboot your machine with diagnostic diskettes or CD-ROM disk.
2. Choose the Service Aids option from the Function Selection menu.
3. Choose the Disk Media option.
4. Choose the Format Disk and Certify option to format and certify your disk drive.
Note: You can also use the diag or smit diag commands to reformat a disk drive. Repeat steps 2 through 4.