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Boot Partition Created During Setup Limited to 4 Gigabytes

This article was previously published under Q119497
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The size of the boot partition generated by Windows NT setup is limited to4 gigabytes (GB) because Windows NT Setup must first format the partitionto the FAT file system. Although it is possible to select NTFS for the bootpartition during Setup, this partition is first formatted to FAT, Setupcompletes, then the partition is converted to NTFS. Because the FAT filesystem is limited to a 4-GB partition size, the boot partition for WindowsNT is also effectively limited to 4 GB.
Windows NT versions 3.1 and 3.5 Setup does not load the full Windows NTKernel and related drivers, so it is not possible for Setup to read an NTFSpartition. During setup, even if you choose NTFS for the boot partition, itmust be formatted to FAT (limited to 4 GB) so that Setup can write to it.Thus, the Windows NT boot partition is limited to 4 GB.

Move the hard drive to another system running Windows NT and attach it tothe same make, model controller as on the original system. Run diskadministrator and make a larger NTFS partition of up to 7.8gb formatted. Aslong as the drive is being translated, the partition table entry shouldcontain valid starting Cylinder, Side, and sector values used for booting.The drive can then be moved back to the original system and ready forWindows NT installation.

Starting and Ending Cylinder, Side, and Sector

The Starting and Ending Side, Cylinder and Sector fields are very importantwith respect to how Windows NT interacts with the disk.

The maximum number of Sides (read/write heads) that can be represented with1 byte is 256. The maximum number of Cylinders that can be represented with10 bits is 1024. The maximum number of Sectors that can be represented with6 bits is 63 because Sectors start counting with 1 (versus Cylinders andSides which start counting with 0).

With a standard sector size of 512 bytes, the 24 bits used to record thestarting and ending sector addresses translates into a maximum possiblepartition size of 7.8GB (8,455,716,864 bytes) which can be described withthese fields. This is particularly important because the same field sizesare employed by the INT 13 BIOS interface which defines how the system BIOSinteracts with the hard disk and is used while booting.

For additional information on file system limits in Windows NT, please seethe following article in the Microsoft Knowledge Base:
ARTICLE -ID: 114841
TITLE : Windows NT Boot Process and Hard Disk Constraints
prodnt maximum

Article ID: 119497 - Last Review: 02/28/2014 04:15:24 - Revision: 2.1

Microsoft Windows NT Advanced Server 3.1, Microsoft Windows NT Workstation 3.1, Microsoft Windows NT Advanced Server 3.1, Microsoft Windows NT Workstation 3.5, Microsoft Windows NT Workstation 3.51, Microsoft Windows NT Workstation 4.0 Developer Edition, Microsoft Windows NT Server 3.5, Microsoft Windows NT Server 3.51, Microsoft Windows NT Server 4.0 Standard Edition

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