---

 

From WinNT in the mid 1990s to Windows-8 there has been a bootmanager built-in to Windows that can be configured for dual or multibooting. This bootmanager can reside inside Windows on the same partition, or it can be on another partition that may or may not have another install of Windows on it. Up to and including Windows Vista it was the default that the first operating system installed on a computer would have the bootmanager inside of it. Further installs of Windows would not get their own bootmanager but be configured to use the existing bootmanager.

The partition with the bootmanager on it will be called the System partition and the partition with the install of Windows that the bootmanager has booted will be called the Boot partition. If the bootmanager and the booted Windows are on the same partition then that partition will be labeled as both the System and Boot partition. If the bootmanager and Windows are on different partitions then we will have separate System and Boot partitions. It is important to understand that a Boot partition that relies on a System partition will not have its own bootmanager, hence Windows installs on separate Boot partitions are not independently bootable.

It is not always obvious if a machine is employing separate System and Boot partitions. Or you may just be unsure which is the System partition with the bootmanager files on it and which is the Boot partition that a Windows install is running from. The easiest way to check is to open the Windows Disk Management utility where you will see the status of partitions clearly labeled for a range of attributes, including System and Boot.

---

 

---

---

 

From Win-7 it became the preferred configuration to put the bootmanager on a separate small partition that was specifically created and reserved just for the bootmanager. If given free reign the Windows 7 and 8 install routines will automatically create this small System Reserved partition and so even if you only have one operating system on a computer you may still have separate System and Boot partitions. The size of this partition can vary but typically Win7 will make it 100MB, and Windows-8 will make it 350MB in size so that there is room enough to also place the WinRE (windows recovery environment) files there instead of on the same partition as Windows. The System Reserved partition can also be used for configuration data for the WIndows BitLocker drive encryption system, removing the need to create a new partition before BitLocker can be enabled.

Subsequent installs of Windows will follow the same pattern as before and all will utilize the existing bootmanager and so when booted will become Boot partitions to the System partition that is the System Reserved partition. Not all Win-7 and 8 machines will necessarily have a system reserved partition as it depends on circumstances at install time if one will be created or not. If not then setup will follow the previous way of doing things and embed the bootmanager, and WinRE, inside the first Windows installed.

Master Boot Record Hard Drives.
All of the above examples are of traditional BIOS based PCs with msdos/MBR partitioned hard drives. On such machines we are only allowed 4 primary partitions, one of which can be made an extended primary partition that can hold multiple logical partitions. The System or System Reserved partition can be any one of the 4 standard primary partitions it is possible to have, which by convention will usually be the first partition on the drive. When there is more than one hard drive it will be the boot drive, the one that the BIOS targets first, that will hold the System partition and so the Windows bootmanager files. A Boot partition can be any primary or logical partition on any internal hard drive, or powered eSATA external drive.

Active Partition.
One primary partition on the boot hard drive in a bios based machine has to be designated as the Active partition before the drive will be bootable. The MBR passes control to the Active partition and so this is the partition that needs to hold the Windows boot files. Hence the Windows System partition is also always the Active partition.

---

 

The new GUID Partition Table (GPT) when used on the boot hard drive in UEFI enabled computers requires a small system partition on the drive that it calls the EFI System Partition (ESP). When Windows-7 or 8 are installed to a GPT styled hard drive they won't create their own separate Windows System Reserved partition but instead utilize this ESP for the location of the Windows bootmanager files. The ESP therefore becomes a combined System Partition for both the GPT configured hard drive and the Windows operating systems.

---

Notice that there is no Active partition showing on our GPT configured hard drive, because in the absence of an MBR on the drive it is the motherboard’s UEFI firmware that passes control directly to a partition, which always has to be the EFI System Partition, thereby making it the unchangeable equivalent to an active partition.

There is also no provision for or need to create extended and logical partitions on GPT styled hard drives because the 4 primary partition limit has been removed. The Microsoft implementation of the new GUID Partition Table can let us have 128 primary partitions, which should satisfy the needs of most normal humans.

---

 

On MBR hard drives Windows-8 creates its larger System Reserved Partition so that there is room to locate WinRE on what will be a combined system and recovery partition. On GPT styled hard drives however the Windows system partition is already combined with the EFI System Partition and so Win-8 will want to create a separate small partition just for WinRE. If allowed to do its own partitioning as install time the Win-8 setup routines will place this new Recovery Partition at the very start of the hard drive, even before the EFI System Partition.

---

 

If given free reign at install time both Win-7 and 8 will if possible on GPT configured hard drives create a small 128MB hidden partition that will typically be labeled MSR (microsoft system reserved) partition. Its location on the drive can vary depending on circumstances, but most often it will be between the EFI System Partition and the Windows partition. As far as we know its sole purpose is to be used by the Windows Dynamic Disk volume management system for configuration data. It will be completely invisible and inaccessible to Windows, but it will show up in many third-party partitioning tools such as GParted and Partition Wizard, and also in the Windows command line DiskPart tool. If Dynamic Disks are never going to be used on a machine then this partition can be omitted when manually creating partitions for Windows installations.

If you find you already have an MSR partition between other required partitions then we recommend just leaving it alone as it can’t do any harm. We would advise against resizing an ESP partition to take over the space and we always advise against moving the starting position of existing Windows partitions. We also suggest you don’t just delete it as we have some reservations that it may not be wise to leave empty space between partitions on GPT configured drives.

---

 

---

If you don’t want the recovery or hidden MSR partitions then they can be excluded at install time of Windows by manually pre-configuring hard drive partitions in a specific way. If a drive already has an EFI System Partition then all we have to do is ensure that there is no unpartitioned space on the drive for any new partitions to be created. For example if we have the EFI partition first, then the partition for our Windows install, then the rest of the drive as either a data partition or just a temporary partition we have created to fill the space, then the recovery and MSR partitions will be left out of the mix.

Note that in the absence of a dedicated Recovery Partition the WinRE files will be placed on the Windows partition. If you do actually want to have WinRE on the hard drive then it is better for it to have its own partition. If you want to exclude WinRE completely from a hard drive then you can leave unpartitioned space after the Windows partition so that separate recovery and MSR partitions are created, which you can later delete.

If you need to create an EFI System Partition then start by making a standard Fat32 partition. It needs to be aligned to 4K partition alignments and on current Advanced Format hard drives it should be 100MB in size, (for native 4K drives it should be 260MB). The ESP partition can be located anywhere on the drive, but we would put it first. The attributes of the partition then need to be set correctly to define it as ESP and this can be done from the GParted partitioning utility by setting the boot flag.

---

 

 

---

 

---