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**Paul** · 10-07-2004, 02:51

The following applies to Windows NT, but these limits have, AFAIK, been carried forward into W2K and XP and most likely increased.

Quote:

File Systems
FAT and HPFS both have internal limits of 4 GB due to the fact that they use 32-bit fields to store file sizes. NTFS uses 64-bit fields for all sizes, permitting its data structures to handle volumes up to 2^64 bytes (16 exabytes or 18,446,744,073,709,551,616 bytes).

This value is the theoretical limit for the NTFS file system. Practical limits having to do with the maximum allowable partition size described above limit the size of an NTFS partition to approximately 2 terabytes. Because the 32-bit fields of the partition table refer to the number of sectors in the partition, disks with larger sector sizes translate into larger permissible partition sizes. Currently Windows NT supports sector sizes up to 4 Kilobytes. With 4KB sectors, Windows NT can support a 16 terabyte partition. As new hardware or software schemes become available, NTFS will be able to handle substantially larger volume sizes.

Drive and Controller Types
IDE drives use a different data structure for representing the number of cylinders, heads, and sectors per track than the partition table and BIOS INT 13 interface. According to the IDE specifications, the maximum number of cylinders is 65536, the maximum number of heads is 16, and the maximum number of sectors per track is 255. This yields a maximum of 136.9 gigabytes, but because the BIOS/IDE interface has been constrained to use the lowest common denominator, the result is a limit of about 528MB for an IDE drive on an Intel-based ISA bus computer. There are new drives and drivers which use an "Enhanced Drive Parameter Table" to translate between the logical sector layout internal to the IDE drive and the logical sector layout addressable by the BIOS INT 13 interface. These drivers and devices can support larger disks. The SCSI II command set uses its own form of sector addressing which currently supports disks as large as approximately 7 gigabytes.