Disk Allocation

Large LUN support was added to Windows NT 4.0 Server in Service Pack 4 (SP4) and later service packs. This feature works only if the associated storage devices support the SCSI REPORT LUNS command. After you install SP4 or later, you may need to addthe following registry value manually:

HKLM\SYSTEM\CurrentControlSet\Services\DriverName\Parameters\LargeLuns

The value should be a REG_DWORD value with a data value of 0x1.

Note that DriverName is the name of the driver for which you want to enable Large LUN support. This causes all HBAs that are controlled by the specified driver to have Large LUNs enabled. Also note that "LargeLUNs" is plural.

>>> Microsoft recommends Windows NT 4.0 Service Pack 6a (SP6a) for Windows NT 4.0-based servers that use LargeLuns. <<<

See Microsoft article Q310072 titled, "Adding Support for More Than Eight LUNs in Windows Server". That article states the following:

When you configure a server with more than eight LUNs, the hardware vendormust be involved in the planning and configuration. There may be several different ways to achieve the configuration you want; the hardware vendor is best equipped to supply the necessary information. This article is not meant to be all-inclusive because of the various implementations that a hardware vendor can use. Contact your hardware manufacturer to determine if and how your hardware can support more than eight LUNs. Windows Server products support up to:

8 buses per adapter
128 target IDs per bus
254 LUNs per target ID

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http://support.microsoft.com/directory/article.asp?ID=KB;EN-US;q310072

There is more in the article than I pasted here.

(REMOVE SPACES from the pasted URL.)

Good luck,

Maxwell