I recently posted a question to Super User about accidentally marking my external HDD's partition as Active and how I could undo my accidental mistake. I followed the instructions provided and they worked fine. This involved some command line magic and from what I understand, I did not have to really do this, but I just wanted to get things back to how they were originally. After making the fix things went back to normal in disk management. After I restarted my computer though i had an issue:

BOOTMGR is missing

Press Ctrl+Alt+Del to restart

Rugh roh! I brought my laptop to work so I could search for a solution on my work computer and I found a nice guide on fixing the issue. To summarize the instructions, I had to reboot with my Windows 7 install disc and click the Repair button. Once there I could then repair the start-up options. One of the commenters on the site claimed you need to do this twice, as the first time the "repair" doesn't actually fix it. I found this to be true as well. I tried to repair it and it did some work, then rebooted. I then got the same error again. I booted from the CD again and repaired the start-up options then after this second time Windows started to boot up. Before the restart I got a nice info window telling me that it did make repairs to the boot info (this was promising).

I've been using Windows 7 for a few days now with no problem, but I just recently noticed that I now can see the System Reserved partition in Computer:

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I immediately went to disk management to see what was up. I noticed that my System Reserved partition is no longer marked as System and instead I believe the repair operation made my C: drive the system partition. I'm not fully aware of what the System partition really is but I briefly read that its a Windows 7 thing that gets created on install of Win7 that writes some BitLocker encryption stuff to a isolated partition as well as some boot files.

enter image description here

  1. How can I undo this and make the System Partition marked as System instead of my OS C: partition?
  2. How can I make it so that I don't see this partition in Computer (I believe fixing #1 will fix this)
  3. What are the implications of what the current state is and the fact that I can now browse into this new partition?

2 Answers 2


The System volume (also known as the "Active volume") is where the boot manager (BOOTMGR) is located, which is where control goes after BIOS. The boot manager is responsible for loading the operating system.

The Boot volume (also known as the "OS volume") is where the Operating System is stored. In your case Win7.

I know. The naming is ridiculous. You use the System volume to boot and your Operating System is on your boot volume. The naming is often confused, even within Microsoft documentation.

Prior to Win7, a clean install of Windows would, by default, create a single C: volume that was both the System volume and the Boot volume. In Win7, this changed to facilitate enabling BitLocker as the boot manager can't be encrypted or you wouldn't be able to run it. So in Win7, a separate 100 MB System partition is created for BitLocker while the rest of the disk is used for the OS volume.

To answer your questions:

1 - You don't need to do anything (see 3), but there is a command line tool included in Win7 specifically designed to move BOOTMGR out of your Boot volume to a different (or new) volume and mark the other volume as Active. From an elevated cmd prompt, run

bdehdcfg -target X: merge

(where X: is your system reserved volume)

2 - Go to Start > diskmgmt.msc. From Disk Management, right-click the partition and click Change Drive Letter and Paths -> Remove -> Yes. Removing the drive letter just hides it from My Computer.

3 - Your current state is fine. You're probably wasting space with your reserved partition, but other than that there's no problem as long as you don't start randomly deleting critical boot files. You're in pretty much the same state that Windows was in by default up through Vista. The state will prevent you from enabling BitLocker on your OS drive, but the BitLocker Wizard will automatically reconfigure your drives for you to put them in the required state for BitLocker.


A few answers for you

2) In Disk Management, right-click the partition and click Change Drive Letter and Paths -> Remove -> Yes. This will leave the partition intact but remove it from 'My Computer', as you requested

3) This thread does a high level job outlining that the system reserved partition is in fact where the boot manager resides in a clean install of Windows 7. The repair you performed rebuilt this partition, but on your C: drive. Browsing it is fine, but if you were able to gain delete privileges, erasing directories/files would probably cause stability or boot problems.

...1) Is trickier. I'm not seeing a definitive way to move the MBR to make the other partition your Boot Partition, at least in Windows 7. I dug out this Vista article about using the command line for MBR repair so you may gleam what you need from that. Furthermore, I could be completely off-base here but making the System Reserved partition 'Active' (Right-click ->Mark Partition as Active) could be what you're looking for as well, but doing that means you are in a closed loop because You can only mark a partition as active on a master boot record (MBR) disk.. Moving the MBR then marking as Active is probably your ultimate goal.

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