Rack System State and Rack Power State Descriptions

When a user powers on the ATECCGEN2 rack, the Rack Control Unit (RCU) loads firmware and runs the RCU service. The RCU service begins initializing components in the rack, enabling gRPC server communication, enabling RCU service status logging, and enabling system monitoring and control. The RCU service reports four system states during the initialization process: Inactive, Init1, Init2, and Operational. When the RCU service is terminated, it transitions from the Operational system state to the Deactivating system state and then the Inactive system state. In the event of an unrecoverable error in the system, the RCU service enters the Halt system state.

System and Power State Transitions

The following figure illustrates rack system state and simplified power states transitions.

Figure 1. System and Power States


  1. Exception-triggered transition
  2. Emergency off (EMO) transition
  • Inactive—The RCU service is not running. The gRPC server communication and RCU service status logging are not available. The system transitions to the Init1 state after the RCU service starts.
  • Init1—The RCU service starts and initializes basic devices on the system, including the status LED. The gRPC server communication is started and RCU service status logging is enabled. The system automatically transitions to the Init2 state after the initialization is completed
  • Init2—The RCU service completes the remaining devices initialization and starts the rack health monitoring. The system automatically transitions to Operational state after the initialization is completed.
  • Operational—The system is fully operational. The power state is either Running or Standby.
    1. The rack power state starts with the Standby state where the rack does not supply power to the payloads.
    2. When the rack power state is in Standby state, pressing the power button on the rack or programmatically calling the SetRackPowerStateToRunningAsync function from a host changes the rack power state to Running and the system supplies power to payloads.
    3. When the rack power state is in Running state, pressing the power button or programmatically calling the SetRackPowerStateToStandbyAsync function from a host causes the system to turn off power supplies to the payloads and changes the rack power state to Standby.
    4. If a catastrophic event happens when the rack power state is in Running state, pressing the Emergency Off Button (EMO) immediately causes the system to turn off all power supplies to payloads and the system unconditionally transitions to the Standby power state. The system remains in Standby state until the RCU service is terminated or encounters a catastrophic error.
  • Deactivating—When the RCU service is terminated asynchronously by calling the InitiateRackRestartAsync function from a host, the RCU service enters the Deactivating state before going into the Inactive state. All running tasks are terminated and resources are freed before the RCU service exits.
  • Halt—the RCU service enters the Halt state in the event of an unrecoverable system error. The Halt state persists indefinitely until the system is deactivated asynchronously.

    In the Halt state the system terminates most of the services except for the gRPC server to allow host communication and RCU service status logging. The RCU service may also transition to this state in the event of critical errors in the Init1, Init2 or Operational system states.