After upgrading to Windows 10 version 1903 (19H1), the Disk Management window may display an additional drive named PortableBaseLayer with a capacity of 8191MB (8GB).
When right-clicking on the PortableBaseLayer drive, all options (except Properties ) will be greyed out.
PortableBaseLayer also appears in the Optimize drives window as a virtual hard drive. You may be wondering what exactly is PortableBaseLayer. The answer will be in the following article.
What is PortableBaseLayer partition?
Please confirm PortableBaseLayer is not a virus or malware partition. PortableBaseLayer is a system partition created for Windows Sandbox.
When you turn on Windows Sandbox, the operating system will automatically create a PortableBaseLayer partition and place all the important files needed to run the sandbox.
Depending on your usage, the partition size will range from 1GB to 10GB. Sometimes, it can even go beyond that range.
In case you didn’t know, Windows Sandbox, as the name implies, is an integrated sandbox that allows you to check programs and settings without affecting the host operating system. Compared to traditional solutions like VMware and VirtualBox, Windows Sandbox is lighter, faster and easier to use.
Windows Sandbox is enabled by all professional and business users as long as the system meets the minimum requirements.
What is PortableBaseLayer appearing in Disk Management?
PortableBaseLayer is not a malicious drive. It is a mounted virtual drive (.vhdx) and used by the Windows Sandbox feature.
If you run the
mountvol command from the Command Prompt, you can see the GUID of the PortableBaseLayer volume and the associated file / folder ( Windows Containers BaseImages ).
The PortableBaseLayer drive is not expected to show up in the Disk Management or Optimize Drives listings . And, in Windows Insider build 18912, some users reported that the drive is not listed in Disk Management.
Are not! PortableBaseLayer has nothing to do with the Reserved Storage feature (also introduced in v1903).
Reserved Storage is a reserved drive created to store Windows Update temporary files and updates, for a smooth installation experience. It has nothing to do with Windows Sandbox or PortableBaseLayer virtual drive.
Reserved Storage is introduced automatically on devices that come with version 1903 preinstalled or devices with a “clean” 1903 installation.
You can learn more about Reserved Storage and how to disable it in the article: How to disable Reserved Storage on Windows 10.
How to find the partition PortableBaseLayer
Finding a Windows Sandbox partition is not difficult. You can use the built-in drive management tool and any other third-party partitioning software.
1. Open the Start menu, search for “Create and format hard disk partitions” and open it.
2. You will see the PortableBaseLayer partition listed in the Volume section .
Note : If you don’t see special partition, it means you don’t have Windows Sandbox enabled yet.
Is it possible to delete PortableBaseLayer partition?
No, do not manually delete the partition as it may damage the Windows Sandbox.
Manually deleting partitions can even cause problems for the host system and other apps like Windows Defender. The good thing is, when you turn off the sandbox feature, Windows will automatically delete that partition for you. You don’t have to do anything.
- Here’s how to delete the Recovery partition and the 450 MB Recovery partition on Windows 10