I accidentally hit "Mark Active" for a logical drive

[Spin]

While working on my Win2k server, I accidentally hit the "Mark Active"
selection after right-clicking a drive. I cannot und-do this setting. It
is simply a logical drive on the system, on a second physical disk. How can
I un-do this change?

 

[Spin]

What is the significance of it? Is there a good explanatory URL handy?

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[Pegasus \(MVP\)]

All Microsoft operating systems boot off the "active" partition
of the primary master disk. If no partition is marked "active" then
you cannot boot.

The "active" attribute on partitions of the other three disks is
ignored.