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If you're like me, then you've supported users who have gathered just enough Windows power user skills "to be dangerous." Some of these individuals happen upon the Disk Management console, see the hidden System Reserved partition on their system, and want to "experiment" with it, believing the partition to be unnecessary.
Of course, those of us with a bit more experience know that under most circumstances, we don't want to mess with this partition. To that point, though, how would you answer the question "What is the purpose of the System Reserved partition, anyway?"
As it happens, the System Reserved partition is an unlettered system drive that is automatically created by Windows 7, Windows 8, Windows Server 2008, and Windows Server 2012 during a clean installation.
In Windows 7 and Windows Server 2008, the partition is 100MB. In Windows 8 and Windows Server 2012, it is 350MB.
The three crucial functions provided are as follows:
- Boot Configuration Store
- BitLocker Drive Encryption
- Windows RE
In this blog post I will first show you how to view the contents of the System Reserved partition. Next we'll cover each of the three functions of the partition. Finally, I will teach you how to delete this partition, which is sometimes a necessary troubleshooting step when you reinstall Windows. Let's get to work!
Viewing the System Reserved Partition
Open up the Disk Management console and you'll see why the System Reserved partition is invisible by default--Windows doesn't associate a drive letter with the partition. I show you the interface below:
You can view the System Reserved partition from DISKPART or the Disk Management console.
All you have to do to view the contents of the System Reserved partition is to attach a drive letter to the drive. To do this, right-click the partition and select Change Drive Letters and Paths from the shortcut menu.
Because all of the contents of the System Reserved partition are hidden, you'll need to open the Folder Options dialog box, enable the Show hidden files, folders, and drives option, and disable the Hide protected operating system files (Recommended) property.
As you can see in the screenshot below, you can view the partition once it has a drive letter designation and you've revealed hidden system files.
Once you've done your homework, you can view the contents of the System Reserved partition
Here is a quick breakdown of the partition-specific file system contents.
- Boot: This folder contains the boot configuration database and supporting files
- Recovery: This folder contains the Windows RE environment that is invoked during the system repair process
- bootmgr: This file is responsible for locating the active partition and parsing the Boot Configuration Database to load an operating system
- BOOTNXT: This file's purpose is largely unknown to...well, just about everybody. I believe that the file has to do with CPU Never eXecute (NX) technology. Let me know in the comments if you read or hear anything different.
- BOOTSECT.BAK: This file is a backup of the computer's boot sector, which is responsible for locating bootmgr and completing an OS load
The Boot Configuration Data Store
The Boot Configuration Data (BCD) store was introduced in Windows Vista (blech) and fundamentally changed how Windows computers start up. The BCD is physically a binary file in much the same format as the binary Registry hives. Therefore, we need a special tool to view and manipulate the BCD just like we need a Registry editor to modify the Windows Registry.
To that end, we can use the built-in BCDEdit command-line tool, or a third-party utility like the wonderful EasyBCD from NeoSmart Technologies. I show you this interface in Figure 3.
EasyBCD gives you complete control over the BCD
The bottom line, friends, is that the BCD and its associated files represent how the system detects how many (and which) operating systems are present on fixed disks, where they are, and how they load during each system startup.
BitLocker Drive Encryption
When you consider the purpose of BitLocker Drive Encryption--that is to say, to encrypt your computer's system volume--the necessity of the System Reserved partition becomes clear immediately.
In short, the BitLocker pre-startup authentication and system integrity verification occur on the System Reserved partition. In Microsoft's literature, they confusingly refer to the System Reserved partition as the system drive.
Windows RE
Windows Recovery Environment (RE) is a graphical troubleshooting environment that is based upon the Windows Preinstallation Environment (Win PE) that Microsoft uses so heavily with their enterprise deployment tools.
We can access the Windows RE either by pressing F8 during system startup (the timeout value is absurdly low so you might need to perform a system hack to configure a more appropriate value), or by accessing the new Advanced Startup options in Windows 8.
By booting into Windows RE, we have started the system from a non-system disk and are therefore free to perform troubleshooting tasks on the system partition without hazard of file locking and/or user logon issues. In the next screenshot I show you most of the Windows RE interface, where you can see what diagnostic or troubleshooting tasks are possible.
Windows RE interface in Windows 8
Of course, we can access the Windows RE by booting a computer from the Windows 8 or Windows Server 2012 media. However, the presence of the RE binaries on the System Reserved partition makes it much more convenient for us to get into RE at any time.
Deleting the System Reserved Partition
In my humble opinion, you should leave the System Reserved partition alone. Besides the obvious stuff (this partition contains the boot files, BitLocker keys, recovery environment, etc.), there is the truth of the matter that the partition is incredibly small--you do not need to recover 350MB of space in all likelihood.
I only have one partition on my primary drive. I am running legal copy of Windows 8.1. What am I missing, besides the recovery partition of course?
It’s ok, if you didn’t assign more partitions…
The recovery partition isn’t really a “partition”, but more like a “system reserved area”.
I know this is quite old, but BootNXT is the Graphical version of the Windows 8 Boot Manager, bootmgr is the text version which can be enabled via some arcane sorcery however the Windows Boot Manager in Windows 8 defaults to running bootnxt instead of bootmgr. CPU Never eXecute support is done in the Windows Kernel (which is actually started from NXT, think of NXT kinda like an EFI application which starts the kernel before the system is started fully.)
Hi There,
Thanks for the nice article, i am facing a little problem in trying to change/allocate the drive letter in the windows 8 environment in that when i right click the reserved partition for options, it just nothing but help.
Please suggest how to overcome the issue?
I still don’t know, what exactly creates this partition? The first windows backup? An option during the setup? The first use of Recovery Environment?
Theo, Windows creates the System Reserved partition when you first install Windows on a clean hard drive. So the short answer is “Windows Setup makes it.” Hope this helps, Tim
Something in my system is writing to the change journal on the system reserved partition causing it to grow to 68M out of 100M used. When this happens the system image operation will fail. I can clear the change journal with fsutil and shrink the used space to 33M. Sometime later though that free space disappears. I could resize the partition using partition magic or something similar but I rather get to the root of the problem. Any suggestions?
Windows 10 users might be confused, or maybe it is for GUID partitions (Gpt). For my Windows 10 system not using Gpt, I think the recovery partition is not called “System Reserved”, it just does not have a name at all in the “Volume” column. For my other system using GUID partitions there are other partitions called reserved that are not recovery partitions. Microsoft does things to confuse us intentionally it seems.
Running Win 7 Pro and trying to upgrade to Win 10. But, stops the install because the Reserved Partition only has 25mb free.
How do I enlarge the partition or access the list of all individual files to delete selected large files?
Thanx in advance, RC
My "System Reserved" shows it is 98@ fragmented. Is this a problem and if it is what do I do about it? My system defragger won't defrag it.
Hi, Such a nice information of system hidden partition and how to access it.
Once, we renamed the reserved partition from c: to some other Initial, how do we get back to the original drive letter c:\ . Please say.
Regarding the use of easybcd, can we just explore the reserved partition without renaming the drive letter
Can we just copy the boot folder and other folders from install dvd to the folders in the reserved partition. I think windows expands the compressed file from the installation media.
would you answer me
No reply for my comment. can i expect a reply