Apple Mac Performa 640 series - Manual (Page 107)

Checking for damage on your internal hard disk
You can check for damage on your internal hard disk with the Internal HD
Format program, which is on the Macintosh Performa CD that came with your
computer. You can use Internal HD Format at any time to check for damaged
blocks (segments of the hard disk that cannot reliably be used to store
information).
1 Start up your computer from the Macintosh Performa CD.
See “Starting Up From a CD-ROM Disc” earlier in this section.
2 Click the Internal HD Format button in the Launcher.
3 Choose Scan For Defects from the Functions menu.
If the program finds damaged blocks, it marks them so that the computer will
not store information on them. This process does not harm any information
on the hard disk.
99 Troubleshooting in the Macintosh Environment