It is often beneficial for a WorkflowInstance state to be saved to disk. Not only when a workflow is long running is this required but also to ensure consistency when performing transactions.

When is Workflow persisted:

• Before the WorkflowInstance is completed.
• Before the WorkflowInstance is terminated.
• When the WorkflowInstance Unload or TryUnload functions are called.
• When the WorkflowInstance Unload or TryUnload functions are called.
• When the WorkflowInstance goes idle and the UnloadOnIdle property if the WorkflowPersistenceService is set.
• After the execution of an Activity adorned with the PersistOnCloseAttribute.

When one of these PersistencePoints is reached the WorkflowRuntime will call the WorkflowPersistenceService SaveWorkflowInstanceState function to persist the workflow.