Windows 98 Utility for Checking Bad Sectors

In Microsoft Windows 98, the primary utility used to check hard drive surfaces for bad sectors and resolve file system anomalies was ScanDisk. This article details the role of ScanDisk, explains how its surface scan located and isolated physical disk defects, and covers how the tool operated across both the graphical interface and the MS-DOS environment.

ScanDisk replaced the older MS-DOS version of CHKDSK as the default disk diagnostic and repair utility for Windows 95 and Windows 98. Built to support both FAT16 and FAT32 file systems, it could detect directory errors, cross-linked files, lost allocation units, and physical drive defects.

To check hard drive surfaces specifically, ScanDisk offered two testing modes:

• Standard Scan: Tested the drive's file structure, file allocation tables (FAT), and directory trees for logical errors.
• Thorough Scan: Performed all Standard tests and systematically tested the entire physical surface of the drive for bad sectors.

During a Thorough scan, ScanDisk checked every cluster across the drive platters. If the utility found an unreadable or damaged sector, it attempted to read whatever data remained, moved that data to a healthy sector, and marked the damaged cluster as "bad" in the File Allocation Table. Marking the sector ensured that Windows 98 would never attempt to write data to that physical location again.

Users could run ScanDisk directly from the Windows desktop by navigating to Start > Programs > Accessories > System Tools > ScanDisk, or by right-clicking a drive in "My Computer," selecting Properties, and clicking the Tools tab.

In addition to the Windows interface version, a 16-bit real-mode version (SCANDISK.EXE) was included in MS-DOS 7.1. This command-line version executed automatically during system startup if the computer was shut down improperly, verifying drive health before loading the Windows graphical environment.