Using Windows Stemcells


A “stemcell” is a customized operating system image containing the filesystem for BOSH-managed virtual machines. When deployed, it includes a process, the BOSH Agent, which is pre-configured to communicate with the orchestrating VM, the BOSH Director. The BOSH Agent is responsible for executing and monitoring “jobs” on the VM.

Deployments of Windows Server on PCF currently use a stemcell containing Windows Server 2012R2.

Root Disk Sizing

Note: Root disk sizing has been disabled and the default disk size for Windows cells has been increased. Future releases will provide ephemeral disk support to allow you to configure the size of your Windows cell.

The size of the root disk of a stemcell determines the minimum root disk size of any Windows VM that the BOSH Director can create from that stemcell. The relationship between the disk size of the stemcell and the root disk size of the Windows cells depends on your IaaS, as shown in the table below.

IaaS Windows Stemcell 1200.17+ disk size
Azure 127 GB
AWS 128 GB
GCP 100 GB
vSphere Recommended 128 GB+*

The table bellow applies to Windows Stemcell 1200.16 and previous versions.

IaaS Stemcell root disk size Possible root disk sizes for Windows cells
Azure 127 GB 127 GB
AWS 30 GB 30 GB or larger (for stemcell 1200.9 and later)
GCP 50 GB 50 GB or larger
vSphere Recommended 128 GB+* Same as stemcell minimum root disk size

*Because you create your own stemcell on vSphere, you can control its root disk size. See Creating a vSphere Stemcell Manually for more information.

In the PAS for Windows 2012R2 tile > Resource Config pane, the VM types that you can choose from reflect the disk size constraints in the table above.

Light Stemcells

“Light” stemcells are metadata files used on a public IaaS that enable users to reference and deploy a stemcell without uploading it manually.

Below is the documentation currently available for activating light stemcells for the Runtime for Windows tile:

Stemcell Builds

Below is the documentation currently available for building stemcells for the Runtime for Windows tile:

Create a pull request or raise an issue on the source for this page in GitHub