How Partition Numbers are Assigned in BOOT.INI

Here is a general example of an entry in BOOT.INI:

multi(X)disk(Y)rdisk(Z)partition(W)\<Name of Windows directory>="<OS name>" <optional parameters>

This article will explain how the value of W, as shown in the first example above, is determined. For information on the other parameters, please see the link at the bottom of the article.

The value of W should reflect the partition on which the Windows directory resides. What follows is an explanation of how to determine what that number is.

Consider how individual partitions are evaluated and numbered:

• Partition numbers are assigned beginning with 1 (not 0).
• The primary partitions are assigned numbers first.
• The logical partitions are assigned numbers next.
• Extended partitions are not assigned numbers at all.

Example 1:

Remember: As a hard drive is evaluated for partition numbering, all of its primary partitions are numbered first; then, all of its logical partitions are numbered next; and extended partitions are ignored.

Example 2:

For more information, see the following Microsoft support articles:

BOOT.INI and ARC Path Naming Conventions and Usage
Troubleshooting the Startup Process
HOW TO: Edit the Boot.ini File in Windows XP

The BOOT.INI file can be edited directly using BootIt BM. See How to Edit BOOT.INI (and Other Small Text Files) with BootIt BM for more information.

TeraByte Unlimited also offers a free utility, EditBINI, which makes it possible to edit BOOT.INI from DOS or Windows 95/98/Me when the BOOT.INI file resides on an NTFS partition.