This topic describes the system events of PolarDB instances.
| Type | Event | Description | State | Level |
|---|---|---|---|---|
| Exception | Instance_Failure_End | The instance failure ends. | Executed | Critical |
| Exception | Instance_Failure_Start | The instance failure starts. | Executing | Critical |
| Exception | SyncStatusAbnormal | A synchronization exception occurs. | Abnormal | Critical |
| Maintenance | Instance:SystemMaintenance.Transfer:Scheduled | The instance migration is scheduled. | Scheduled | Warn |
| Maintenance | Instance:SystemMaintenance.Transfer:Executing | The instance is being migrated. | Executing | Warn |
| Maintenance | Instance:SystemMaintenance.Transfer:Executed | The instance is migrated. | Executed | Warn |
| Maintenance | Instance:SystemMaintenance.Transfer:Canceled | The instance migration is canceled. | Canceled | Warn |
| Maintenance | Instance:SystemMaintenance.MinorVersionUpgrade:Scheduled | The instance update to a minor version is scheduled. | Scheduled | Warn |
| Maintenance | Instance:SystemMaintenance.MinorVersionUpgrade:Executing | The instance is being updated to a minor version. | Executing | Warn |
| Maintenance | Instance:SystemMaintenance.MinorVersionUpgrade:Executed | The instance is updated to a minor version. | Executed | Warn |
| Maintenance | Instance:SystemMaintenance.MinorVersionUpgrade:Canceled | The instance update to a minor version is canceled. | Canceled | Warn |
| Maintenance | Instance_Failover | The failure-triggered switchover between the primary instance and a secondary instance starts. | Executed | Warn |
| Maintenance | Instance:SystemMaintenance.ScheduledOperation:Scheduled | The O&M operation on the instance is scheduled. | Scheduled | Warn |
| Maintenance | Instance:SystemMaintenance.ScheduledOperation:Executing | The O&M operation on the instance is being performed. | Executing | Warn |
| Maintenance | nstance:SystemMaintenance.ScheduledOperation:Executed | The O&M operation on the instance is performed. | Executed | Warn |
| Maintenance | Instance:SystemMaintenance.ScheduledOperation:Canceled | The O&M operation on the instance is canceled. | Canceled | Warn |
| InstanceMaintenance | Instance_Switchover | The task-triggered switchover between the primary instance and a secondary instance starts. | Executed | Warn |