Service Reference Guide

Service Reference Guide 4–7
Ultra ATA Drive Guidelines and Features
4.5 Drive Capacities
The combination of the file system and the operating system used in the computer determines the
maximum usable size of a drive partition. A drive partition is the largest segment of a drive that
may be properly accessed by the operating system. A single hard drive may therefore be
subdivided into a number of unique drive partitions in order to make use of all of its space. The
table that follows identifies the capabilities and restrictions imposed on the computer by the
combinations of file and operating systems.
Microsoft to Drive Manufacturer Size Conversion Table*
Drive Size as Identified by
Microsoft Operating System
Drive Size as Identified by
Drive Manufacturers
2 GB 2.1 GB
4 GB 4.3 GB
32 GB 34.4 GB
64 GB 68.7 GB
128 GB 137 GB
2 TB 2.199 TB
*Drive size calculations by drive manufacturers are bytes to the base 10
while calculations by Microsoft are bytes to the base 2.
Drive/Partition Capacity Limits
Maximum Size
File
System
Controller
Type Operating System Partition Drive
FAT 16 ATA or SCSI DOS/Windows 95 2 GB 128 GB
FAT 16 ATA or SCSI Windows NT 4 GB 128 GB
FAT 32 ATA or SCSI Windows 98/SE 64 GB 128 GB
FAT 32 ATA Windows 98/SE with
QFE* and Windows ME
128 GB 128 GB
FAT 32 SCSI Windows 98/SE with
QFE* and Windows ME
2 TB 2 TB
FAT 32 ATA Windows 2000/ XP 32 GB 128 GB
FAT 32 SCSI Windows 2000/ XP 32 GB 2 TB
NTFS ATA Windows NT/2000/XP 128 GB 128 GB
NTFS SCSI Windows NT/2000/XP 2TB 2TB
*For Windows 98/SE with QFE see www.microsoft.com, search for Q263044 for
details on how to expand partition size.