The state of the read request at the time of retrieval of AsyncReadManagerMetrics.
| Unknown | The read request status was unknown. |
| InQueue | The read request was waiting in the queue to be read. |
| Reading | The read request was in the process of being read. |
| Completed | The read request had fully completed. |
| Failed | The read request had failed before completion. |
| Canceled | The read was canceled before completion. |