In most cases, disks are formatted by the manufacturer or reseller and do not need to be reformatted when you install the drive. To determine whether or not a disk is formatted, use the format utility. See "How to Determine if a Disk is Formatted" for more information.
If you determine that a disk is not formatted, use the format utility to format the disk.
Formatting a disk accomplishes two steps:
Preparing disk media for use
Compiling a list of disk defects based on a surface analysis
Formatting is a destructive process--it overwrites data on the disk. For this reason, disks are usually formatted only by the manufacturer or reseller. If you think disk defects are causing recurring problems, you can use the format utility to do a surface analysis, but be careful to use only the commands that do not destroy data. See "How to Format a Disk" for details.
A small percentage of total disk space available for data is used to store defect and formatting information. This percentage varies according to disk geometry, and decreases as the disk ages and develops more defects.
Formatting might take anywhere from a few minutes to several hours, depending on the type and size of the disk.