Windows NT Setup: SCSI Boot Disk Size Limitations

The information in this article applies to:

• Microsoft Windows NT operating system version 3.1
• Microsoft Windows NT Advanced Server version 3.1
• Microsoft Windows NT Workstation versions 3.5, 3.51, and 4.0
• Microsoft Windows NT Server versions 3.5, 3.51, and 4.0

SYMPTOMS

When you attempt to install Windows NT on a computer with a large SCSI boot disk, Windows NT Setup may not recognize the primary active partition. This problem can occur when the boot disk is a single physical disk or when multiple physical disks are represented as one large hard disk by the SCSI drive hardware RAID configuration.

CAUSE

Windows NT Setup does not recognize boot disks, with more than 1024 cylinders.

NOTE: The size of 1024 cylinder disks vary, but typically, they hold one to two gigabytes of data.

WORKAROUND

If your SCSI host adapter can be configured to perform disk geometry to system BIOS translation, you can install Windows NT on a boot disk with more than 1024 cylinders. To do so, enable controller translation and repartition any existing partitions. If necessary, low level format the hard disk before repartitioning. Check with your hardware manufacture for specific advice and details.

If your controller does not support disk translation, keep the boot disk size within the 1024 cylinder limit or purchasing an adapter capable of disk translation.

For more information about the configuration of hard disk drive parameters, query on the following words in the Microsoft Knowledge Base:

   WINDOWS NT and BOOT and PROCESS and IDE

MORE INFORMATION

Windows NT Setup does not recognize an boot disk with more than 1024 cylinders because the Windows NT boot process must initially rely on the system BIOS INT 13 calls (which recognize 1024 or fewer cylinders on the primary active partition). The initial computer boot environment is not operating system specific, and defines the boot parameters before the Windows NT specific boot files (NTLDR and NTDETECT) are loaded. Windows NT cannot change constraints established by the hardware and firmware routines.