EISA Configuration Boot Code Is Replaced on Mirror Drives

Disk Administrator overwrites the EISA partition boot information in the master boot record (MBR) of a secondary mirror when the mirror is established. As a result, the normal EISA prompt does not appear when you boot to the secondary mirror.

Windows NT rewrites the MBR with an industry standard universal boot record whenever establishing or breaking fault tolerance members, such as mirrors, when it updated the partition table.

Most manufacturers use the system BIOS to prompt the user to enter EISA configuration utility. Manufacturers that modify the universal master boot record with their own boot code to prompt the user to enter EISA configuration utilities will exhibit this problem.

HP NetServer Navigator and some other manufacturers' EISA utilities create a small EISA partition on the hard drive so that it can prompt you with a choice to run the EISA configuration at startup.

To have this on both primary and secondary mirror drives, you must first establish the EISA partition separately before installing Windows NT.

If you view this partition in a sector editor like Norton Diskedit or Microsoft Disk Probe (Dskprobe.exe), you will find the partition type to be type 12. To Disk Administrator, this partition is properly recognized as and EISA partition. After installing Windows NT, when you view the master boot record on the secondary drive, but before establishing the mirror, you will see the data in the master boot record that is used to prompt the user for EISA configuration on both drives.

After establishing and generating the mirror, the MBR on the secondary drive is replaced with a universal master boot record, which deletes the EISA prompt information. None of the partition table entries are damaged. The drive is still type 12, although none of the EISA boot information remains.

The third-party products discussed here are manufactured by vendors independent of Microsoft; we make no warranty, implied or otherwise, regarding these products' performance or reliability.

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.