What are three required components of an IBM Spectrum Protect server?

According to the IBM Documentation1, three required components of an IBM Spectrum Protect server are:

Database: The database stores information about server operations, client nodes, storage pools, backup data, and other server-related data. The database is essential for server operation and recovery.

Active log: The active log records changes to the database that occur during normal server operation. The active log is used to recover the database after a system failure or a planned shutdown.

Instance directory: The instance directory contains configuration files, license files, security files, and other files that are specific to a server instance. The instance directory is also used to store temporary files during server operation.

https://www.ibm.com/docs/en/spectrum-protect/8.1.9?topic=servers-whats-new