This topic describes the system events of PolarDB instances.
| Type | Event | Description | Status | Level |
|---|---|---|---|---|
| Maintenance | Instance_Failover | An instance failover occurs. | Executed | Warn |
| Exception | Instance_Failure_End | An instance failure ends. | Executed | Critical |
| Exception | Instance_Failure_Start | An 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 |