In the server, each DCU has its own SPP. An SPP must be present for its DCU to be operational.
If two or more DCUs are combined in one PDomain, one SPP is designated to manage the entire PDomain and is known as the PDomain-SPP. If an SPP must be removed, its DCU cannot be part of a running PDomain.
If DCUs are operating independently of each other, the failure of one SPP in a DCU does not affect the other DCUs.
A TPM (Trusted Platform Module) is located on each SPP and provides a secure keystore used in a PDomain. If you replace an SPP in a system running TPM, you might need to save the current TPM keystore for migration to the replacement SPP. See Remove an SPP and Install an SPP for instructions.