How to Determine the ARC Path

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When you troubleshoot some issues where a Windows NT boot disk is needed, you may need the ARC path for the Boot.ini file. However, it may not be obvious, or the machine administrator may not remember the partition or root directory the operating system was installed in. This information can be recovered from the Emergency Repair Disk.


The Setup.log file is located on the Emergency Repair Disk. It has the system, hidden, and read-only attributes. If this file is opened in a text editor, the first few lines will provide information about how to build the ARC path to the operating system. The following is an excerpt from a typical Setup.log file.

   TargetDirectory = "\WINNT"
   TargetDevice = "\Device\Harddisk0\partition2"
   SystemPartitionDirectory = "\"
   SystemPartition = "\Device\Harddisk0\partition1"

A typical ARC path might be:

   multi(0)disk(0)rdisk(0)partition(2)\WINNT="My Server 4.0"

The rdisk parameter is defined as Harddisk<X> on the TargetDevice line, where <X> is a variable that represents the drive ordinal. Note that the rdisk parameter is not used when SCSI replaces multi in the ARC path.

The partition parameter is defined as partition<X> on the TargetDevice line, where <X> is a variable that represents the partition ordinal. Note also that SystemPartition refers to the partition where NTLDR is stored. Use TargetDevice for the partition ordinal value.

The TargetDirectory line defines the system root directory, which is the part of the ARC path immediately following the partition number.

For more information, please see the following articles in the Microsoft Knowledge Base:

ARTICLE-ID: 102873
TITLE : Boot.ini and ARC Path Naming Conventions and Usage

ARTICLE-ID: 130921
TITLE : Creating an FT Boot Disk With SCSI() and Multi() Identifiers

ARTICLE-ID: 139333
TITLE : Creating Alternate Boot Selections on AXP Machines


Article ID: 155222 - Last Review: November 1, 2006 - Revision: 1.2
  • Microsoft Windows NT Workstation 4.0 Developer Edition
  • Microsoft Windows NT Server 4.0 Standard Edition
kbhowto kbnetwork KB155222

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