.. _restartlow:

==========
Restart
==========

1. Subarry Node provides API for **Restart workflow**.
2. The Sub-array node **accepts the command** if :-
    
    A. Admin mode reported by each of the system - CSP,SDP subarray are in **ONLINE/ENGINEERING/RESERVED**
    B. Operational state of the Sub-array node is **ON/OFF/INIT/STANDBY/ALARM**
    
3. The Sub-array Node **rejects the command** if-
        
    A. Admin mode reported by each of the system - CSP,SDP Sub-array are in **OFFLINE** or **NOT FITTED**.
    B. Operational state of the sub-array node is **FAULT/UNKNOWN/DISABLE** .

4. The following **state requirements** are applied for **the command execution** :-

    A. TMC Subarray is in `'observation state'` **ABORTED** or **FAULT** .
    B. :term:`isSubarrayAvailable` is checked to ensure the subsystems (CSP, SDP and MCCS) are :term:`available`

5. The command execution involves below key operations :-
    A. Active scan timers or command timeouts are cancelled or paused to prevent follow-on automatic actions
    B. Assigned resource record , scan durations ,scheduling block Id etc are cleared.
    C. The command is then invoked on the relevant TMC CSP, SDP, MCCS leaf Nodes after perfroming few key checks as below :
        
        + :term:`available` check is done for the subsystem
        + Subsystem's current observation state is inspected; if already *EMPTY*, *ABORTING*, the abort call for that subsystem is skipped with a log note.
        + Command is then sent to relevant TMC CSP, SDP, MCCS leaf Nodes
        + If leaf node rejects/ faces failure in sending restart command , command failure is reported as **'RESULT_CODE - FAILED'** on Long Running Command Result attribute of the TMC Subarry node.Command will not be sent to remaining subsystems in this case if multiple subsystems are involved .
        + If all leaf node accept command , the TMC Subarry node will wait for command completion.

6. The Sub-array node monitors the progress of command via the Sub-array node ObsState transitions and the long running command results.

    A. Command is successful when the TMC Subarray Node transitions to **EMPTY** ObsState. This is reported as **'RESULT_CODE - OK'** on Long Running Command Result attribute of the Subarray node.
    B. Command failure is reported in any of the below cases as **'RESULT_CODE - FAILED'** on Long Running Command Result attribute of the Subarray node.

        + The CSP Leaf node/SDP Leaf node/MCCS Leaf node reports **'RESULT_CODE - FAILED'** on its Long Running Command Result attribute
        + The command times out if TMC SubarrayNode does not transition to **EMPTY** within the timeout period specified by `CommandTimeOutDefault` property specified in helm chart of the TMC Subarray node .