A task can be in one of the following states: Idle; Waiting; Running; Need interaction. The initial task state is Idle.
Once the task is started manually or the event specified by the schedule occurs, the task enters either the Running state or the Waiting state.
Running
A task changes to the Running state when the event specified by the schedule occurs AND all the conditions set in the backup plan are met AND no other task that locks the necessary resources is running. In this case, nothing prevents the task from running.
Waiting
A task changes to the Waiting state when the task is about to start, but another task using the same resources is already running. In particular, more than one backup tasks cannot run simultaneously on a machine. A backup task and a recovery task also cannot run simultaneously, if they use the same resources. Once the other task unlocks the resource, the waiting task enters the Running state.
A task may also change to the Waiting state when the event specified by the schedule occurs but the condition set in the backup plan is not met. See Task start conditions for details.
Need interaction
Any running task can put itself into the Need interaction state when it needs human interaction such as changing media or ignoring a read error. The next state may be Idle (if the user chooses to stop the task) or Running (on selecting Ignore/Retry or another action, such as Reboot, that can put the task to the Running state.)