Standard Windows 10 Partitions for MBR/GPT Disks
Introduction
The purpose of this article is to help with understanding the standard partitions for Windows 10 installations on both MBR and GPT disks. Note that there are many possible configurations and they can change depending on a number of factors. OEM installations may also have additional OEM tool and/or recovery partitions.
Standard Windows 10 Partitions for GPT Disks (UEFI booting)
The following partitions exist in a normal clean Windows 10 installation to a GPT disk:
- Partition 1: Recovery partition, 450MB - (WinRE)
- Partition 2: EFI System, 100MB
- Partition 3: Microsoft reserved partition, 16MB (not visible in Windows Disk Management)
- Partition 4: Windows (size depends on drive)
Disk Management details for the disk:
The following OEM layout has custom sizes for the partitions and includes an additional recovery (OEM, not WinRE) partition:
- Partition 1: EFI System, 260MB
- Partition 2: Microsoft reserved partition, 16MB (not visible in Windows Disk Management)
- Partition 3: Windows, 465GB - (Windows 10)
- Partition 4: Recovery Partition, 980MB - (WinRE)
- Partition 5: RECOVERY, 10GB - (OEM Recovery)
Disk Management details for the disk:
The following layout started as an earlier Windows OEM installation and changed into its current configuration as a result of multiple Windows upgrades:
- Partition 1: Recovery partition, 1GB - (original Windows WinRE)
- Partition 2: EFI System, 100MB
- Partition 3: Microsoft reserved partition, 128MB (not visible in Windows Disk Management)
- Partition 4: TI10672700E, 223GB - (Windows 10)
- Partition 5: Recovery partition, 500MB - (current Windows 10 WinRE)
- Partition 6: Recovery partition, 8GB - (OEM Recovery)
Disk Management details for the disk:
Standard Windows 10 Partitions for MBR Disks (Legacy booting)
The following partitions exist in a normal clean Windows 10 installation to an empty MBR disk:
- Partition 1: System Reserved, 500MB - (booting files, WinRE)
- Partition 2: Windows (size depends on drive)
Disk Management details for the disk:
The following partitions exist in a normal clean Windows 10 installation to an existing 500GB active primary partition:
- Partition 1: Windows, 500GB - (booting files, WinRE, Windows 10)
Disk Management details for the disk:
The same system as above after upgrading Windows 10:
- Partition 1: Windows, 499GB - (booting files, Windows 10)
- Partition 2: Recovery, 450MB - (WinRE, new partition created with upgrade)
Disk Management details for the disk:
The Windows Recovery (WinRE) Partition and Windows Upgrades
When Windows 10 is upgraded to a new version (1511, 1607, 1703, etc.) it may create a new WinRE partition. This can occur even if the new WinRE files would have fit on the existing WinRE partition or the WinRE files exist on the Windows partition. As part of the upgrade, the Windows partition will be resized smaller and a new partition will be created (usually 450MB, but might be larger). This can cause issues since it changes the partition layout on the disk (backup image chains based on the Windows partition would need to be restarted, for example). It also requires manual cleanup or you end up with multiple useless partitions on the disk.
The partition changes are especially undesired when using multi-booting on an EMBR disk with unlimited primary partitions since Windows may not be aware of existing partitions not loaded into the MBR. Currently, the only method to avoid this issue is to make sure the partition table is full (four primary partitions exist on the disk and are loaded into the MBR) before upgrading. Doing this prevents the Windows installer from creating a new partition as there is no available partition table slot for it. Otherwise, if a new WinRE partition gets created and you want to move the files to the Windows partition you can refer to the following KB article: Removing the Windows 10 Recovery (WinRE) Partition