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Windows 7: Changing Drive Letter of Boot/Active partition

21 Dec 2012   #1

Window 7 Home Premium 64-bit
Changing Drive Letter of Boot/Active partition


The drive letter of my boot/active Win7 partition should be C:, but in my case it isn't; the boot/active partition drive letter is F.

I've tried to move heaven and earth to change the drive letter of the boot partition but nothing works.

So, aren't there any apps, tools or utilities to change the drive letter of my current boot partition?

Thanks in advance,

My System SpecsSystem Spec
21 Dec 2012   #2

Windows 10 64 bit

Nothing that I know of. My original Win 7 installation was "E" drive. I had considered things suggested but finally decided to let it be. It doesn't matter to Windows what the drive letter is, everything works regardless of the drive lettter. I later installed Windows 7 on an SSD drive, with a clean install (and the SSD drive the only drive connected during installation) and now back to the "C" drive.
My System SpecsSystem Spec
21 Dec 2012   #3


You cannot change the Win7 partition letter without ruining the OS.

It will always see itself as C when it is correctly installed from booted installer and not run from another OS which locks out the C drive letter.

During imaging it must also be set to Auto and not choose another drive letter.

If you'll post back a screenshot of your maximized Disk Mgmt drive map with listings, using the Snipping Tool in Start Menu, we can advise you better. But most likely you'll need to reinstall if you want WIn7 on C which works best all around.
My System SpecsSystem Spec

21 Dec 2012   #4

Window 7 Home Premium 64-bit

Here is the screenshot.
Changing Drive Letter of Boot/Active partition-ddbshot.png


My System SpecsSystem Spec
21 Dec 2012   #5


Hi Johan -

I'm not sure where your original C went, but the problem is that Win7 wasn't correctly installed from a booted installer but was instead run from another OS. What I would do is back up your files, boot the installer, in steps 6/7 of Clean Install Windows 7 delete F and create/format a new partition in all of that space before your Logical partitions to install Win7 correctly to C.

Later if you need even more space on C, you can annex space from any other partition using the cool new Partition Wizard Extend feature: How to extend partition easily with partition magic – Partition Wizard video help.

In addition look over this to assure you get/keep a perfect install providing you use only the tools and methods given, which are same for retail: Clean Reinstall - Factory OEM Windows 7
My System SpecsSystem Spec
21 Dec 2012   #6

Window 7 Home Premium 64-bit

Ok, I will reinstall the partition and see if the boot gets the drive letter C:
That will take some time. I'll be back.
My System SpecsSystem Spec
21 Dec 2012   #7

Window 7 Home Premium 64-bit

Thanks, it works, my boot drive now has the drive letter C:

I think I know what went wrong. In the screenshot, drive F: holds a Windows 7 Clean Installation (Win7CL) while drive Z: holds the Windows 7 OEM version (Win7OEM) from Asus with a huge amount of bloatware, but that I would like to keep for a while for testing purposes. I can boot into both Windows version by marking the right partition as active in Disk Mgmt.

Win7OEM was there first, active and non-hidden at the time I installed Win7CL from a 4GB USB flash drive comprising the full clean installation. Probably the clean installer on the USB FD must've detected the Win7OEM, noticed the drive letter was C: and installed then the Win7CL into the left-most partition in Disk Mgmt with the drive letter F: so not to collide with the drive letter from Win7OEM (C.

Now, a few hours ago, I made sure the Win7OEM partition was non-active and I've hidden the Win7OEM partition too using DISKPART in the command prompt:
DISKPART> set id=17 override (after selecting the Win7OEM partition first)

Then I followed your procedure and all was fine. Now I got my C: drive as I always wanted.

Thanks, j
My System SpecsSystem Spec
21 Dec 2012   #8


You're welcome but I'd feel better about it if you better comprehended what happened there. There are others who'll read this so it needs to be clarified.

Again, C is not available during install when the installer is run from it and not booted. And you choose which partition to install upon, so you would have had to choose the left-most partition unless you didn't even pay attention to the drive-selection screen and it defaulted there overwriting God-knows-what.

However if you ran the installer from Z then C should have been available. And why is the factory preinstalled Win7 partition lettered Z? Did you re-image it from a backup image choosing that letter? The confusion mounts. Why didn't you ask here about these things?

Your method to boot is also hinky. If you intend to Dual Boot even temporarily you should add the other OS using EasyBCD if it wasn't added during install as it should have been. Then either set the Menu timeout low to 5-10 seconds or less, or set it to 0 to be adjusted in the Startup tab of System>Advanced System Options.
My System SpecsSystem Spec
21 Dec 2012   #9

Window 7 Home Premium 64-bit

Ok, I'll tell you the whole story.

Up until a few months ago I had only the Win7OEM partition on the left-most side in Disk Mgmt; so there was only ONE version of Windows on my computer. I decided to install a Clean Installation (Win7CL) without removing the Win7OEM because I wanted to keep it for testing purposes. So I shifted the Win7OEM partition from left-most to the very right side in Disk Mgmt where it sits now. I did that with GPartEd; fast and easy.

Then, I created a new partition on the left-most side in Disk Mgmt, so on the highest data-rate tracks of the HDD. Reason for that is that I wanted to have a fast working Win 7 Clean Installation.

I then installed the Win 7 Clean Installation from a USB Flash Drive (UFD), so NOT from the Win7OEM partition, onto the left-most empty partition, which was prepared for the Win7CL. All went fine; I didn't pay attention at that time what drive letter the UFD Clean Installer in the drive-selection screen was associating to the newly prepared left-most partition; it turned out later that it associated the letter F to the Win7CL volume.

After the Win7CL was installed, I rebooted the computer and a boot selection menu appeared with 2 Win7 versions; the first one pointed to the Win7CL and the second one pointed to a recovered version, which was the Win7OEM. That boot menu (BCD file) sat (and still sits) in the Win7OEM partition, which was still marked as active in Disk Mgmt.

I cannot remember the details but I think I made the Win7OEM partition hidden, marked the Win7CL as active and had to repair (with the repair disk) the Win7CL to make it bootable. I edited the Win7CL boot menu with EasyBCD so to have the possibility to boot into both Win7CL and Win7OEM in case the Win7CL partition was marked as active. Now I was in a situation where I always got a consistent boot menu with 2 Win options, whatever Windows partition was marked active in the Disk Mgmt. That way I could always boot into one of the 2 Win versions in case of random boot failure of one of the 2 Win partitions. And yes, the time-out was 5 seconds in both boot menus.

However, I noticed that when booting into Win7OEM the Win7OEM drive letter was C, while the Win7CL partition drive letter was F. But when I booted into Win7CL, the Win7CL partition drive letter was also F, it did not change to C, while the Win7OEM partition drive letter remained at C.

That was the situation for the past couple of months and all was fine, except for the drive letter of the Win7CL partition, which was always F.

Then, this afternoon (21 Dec. 2012) I figured to clean up the drive letters while being booted into Win7CL. For all partitions it worked, including the Win7OEM partition which got the drive letter Z, but it did not work for the Win7CL partition itself, and that is why I posted my problem this afternoon.

As explained in my post #7 the problem is now solved.

Thanks, j
My System SpecsSystem Spec
21 Dec 2012   #10


Let's see if I've got this correct with the additional puzzle pieces you added

click to enlarge

You somehow moved your Factory OEM C partition to the other end of the drive using ancient Gparted, in order to Clean Reinstall in the lower HD address. Looking at the screenshot OEM is now Z so one would assume it had its letter changed during transfer as some imaging suites allow. But now you report you just changed it yourself in Win7 which is allowed since you're not booted into it and it has only a placeholder letter in your Clean Install's Disk Mgmt. But since in screenshot your Clean Install is booted and on F, I had wondered why the original OEM install wasn't still showing C even though not booted.

But you're saying that when you boot into the OEM clone/copy/image it definitely is C, correct? There's no way for us to know this from the screenshot, until you just told us.

However this doesn't change the fact that when the Clean Install was run the installer was not correctly booted so that Win7 will see itself as C, as it does with the installer correctly booted to install. It was obviously run from C or it would now be C instead of F. This never varies in countless thousand installs we've seen. Even if there are multiple other OS's on C, Win7 will always be C when booted, when installed from boot.

My head is spinning from trying to sort the puzzle, and when I just went to copy the screenshot to here I am reminded that you reinstalled today over F. So may I ask if both installs now see themselves as C when you boot into each?
My System SpecsSystem Spec

 Changing Drive Letter of Boot/Active partition

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