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Can't change boot volume drive letter!

by roopie / February 25, 2005 12:12 PM PST

I just re-built my XP Pro SP2 system, and for some strange reason the boot volume, which should normally be drive letter "C" is actually drive letter "G" in the rebuilt system. If I go into Disk Management and try to change it, I get the error message "Windows cannot modify the letter of the boot volume or system volume". However, it seems to me that I have done this in the past, and that there is a way around this. Can anyone point me in the right directin? How do I change my root back to "C"?

Thanks for any and all assistance!

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System and boot partion lettering
by ParnaoidGuy / February 25, 2005 12:32 PM PST

Short answer is .. you can't.

There are several reasons why, but the two most pertinent is:
1 There is only one c:drive. Thats the active primary partion of the boot drive. This is your system partition. The boot partition is where the OS lives. I know, the naming is messed up, but it makes a wierd kind of sense. You don't actually complete booting until you get to the OS.

Since the letter is not c: then I will assume that you have more than one partition or drive.

As a tangent , I would question why you would have more than one partition. Regardless of what many experts will tell you, there are few real benefits to multiple partitions. Like the page file myth. But I digress.

2 During the boot process the drive letters are not even referenced, the XP boot uses the ARC paths defined in the boot.ini. ARC paths are a succinct way of referancing drives, controllers, and partitions .

Theoretically, correctly written sub routines and programs will referance the OS by using relative pathing.

BUT, the OS itself referances its own variables and pathing with absolute pathways in the registry as well as several configuration files. These are created during install and form a foundation on which everything else is laid. There is no viable way that will ensure a stable system that can change this.

Bear in mind, you can change any partitions letter that does not contain these key files easily. You can even supply more than one path, or unix like and mount volumes in volumes....but again, I digress.

Hope this helps.

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Re: Can't change boot volume drive letter!
by JamesJ / February 25, 2005 3:29 PM PST

I assume you have other drives/partitions in your system. When I installed XP it was on a second hard drive, with Win98 on the first drive and partitions scattered across several drives. The WinXP boot drive ended up being named F: instead of C:. AFAIK, this should not normally be a problem, but I wanted the drive to be C: like I was used to, so I actually disconnected my other drives and re-installed XP. That's one option.

I seem to recall reading that it might be possible to change the Windows XP boot drive letter. I don't remember the details, but it may have involved some changes in the registry. Personally, I don't think I'd try it, but if you're interested, maybe someone else can point you to some instructions.


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The drives in the system are...
by roopie / February 27, 2005 12:20 AM PST

...2 physical hard drives, and 2 CD-ROM/DVD drives. I installed the OS and system files onto a freshly formatted 20 gig primary hard drive. The 2nd hard drive is hard wired as the secondary, and contains 2 partitions containing just archives and data, no program files. None of the drives have "C" as a designation, so this letter is available. It's just that when I installed XP on the new drive it was assigned "G" for some reason...

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Your backup will be tested if you do this!
by R. Proffitt Forum moderator / February 27, 2005 12:27 AM PST
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Re: The drives in the system are...
by JamesJ / February 27, 2005 1:19 PM PST

> None of the drives have "C" as a designation,
> so this letter is available.

It doesn't work that way. Every time Windows starts, it scans the available hard drives looking for DOS/Windows "drives" and assigns drive letters to them as it finds them. I forget the details, but basically, it looks for primary DOS/Win drives first, then drives in extended partitions. Somewhere in there it also looks for removeable drives and assigns drive letters to them as well. You can probably find the details in the MS knowledgebase or elsewhere online, but the point is, the drive letters aren't permanently assigned. For example, if you have a single hard drive with C: and D: on it and then plug in a second hard drive with another DOS/Win drive on it, when you restart Windows, the second drive could end up being D: and what was D: is now E:. It depends on what types of partition they are, primary or extended.

Windows XP apparently goes through this same kind of drive enumeration process during installation, assigning drive letters to the DOS/Win drives it sees and then assigning the next available letter to the drive it's installing in, so if it sees other drives (aside from a CD/DVD drive), the Win XP boot drive may not end up being C:. This is what happened to me, and presumably to you.

If you want the boot drive to be C:, disconnect the second hard drive and (just to be sure) the second DVD/CD drive, then re-install Win XP in the first partition on the hard drive. If you've got other DOS/Win partitions on that first drive, you might even need to remove those before re-installing WinXP (not sure about that).

Or you could try the thing about changing your WinXP boot drive without re-installing. Like I said, I don't think I'd try it, partly because this is a pretty fundamental change and I'd be worried that even if it seemed to work, there might be some problem lurking that wasn't immediately obvious, but could screw up the system later.


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This is how to restore the system/boot drive letter...
by Edward ODaniel / February 26, 2005 1:16 AM PST
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by Merl Priester / February 27, 2005 3:35 PM PST

You cannot change the letter XP was installed to.
Unplug all drives except the C: drive and re-install XP
clean. Then plug in the others.
1 hard drive
1 cdrom
NO Zip drives at install time.

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