how to view and manage scheduled events - PolarDB - Alibaba Cloud Documentation Center

You will be notified of scheduled events on your PolarDB cluster, such as software upgrades and hardware maintenance, by SMS, voice call, email, internal messages, or through notifications in the console. On the scheduled events page, you can view details like the event type, task ID, and cluster name, and modify the switchover time.

Precautions

If you have pending maintenance events, you can find notifications in the left-side navigation pane of the console by choosing Event Center > Scheduled Events.
We typically notify you of a scheduled event, such as a database software upgrade or hardware maintenance, at least three days in advance. Notifications can be sent by voice call, email, internal message, or through the console. To receive these notifications, log on to the Message Center, enable Cloud Database Fault or Maintenance Notification, and specify the message recipients. We recommend specifying your database O&M engineers as recipients to ensure they receive the alerts.

Figure 1. Notification settings in the Message Center
For questions about scheduled events, join our DingTalk support group by searching for the group number 51685000218. In the group, you can mention an expert with your question or use the 24/7 PolarDB chatbot for assistance.

Procedure

Log on to the PolarDB console.
In the upper-left corner, select the region where the cluster is deployed.
In the left-side navigation pane, click Event Center > Scheduled Events.

Note
A pop-up window appears for maintenance events that require scheduling. Schedule the event as soon as possible.
Optional: On the Scheduled Events page, configure a periodic schedule.
1. On the right side of the page, click Periodic Time Settings.
  
  Note
  Periodic Time Settings is a global configuration for proactive database maintenance events, excluding emergency risk-fix events. After you set a periodic schedule, the switchover time for new proactive maintenance events is automatically scheduled within the specified period. If you do not set a periodic schedule, the switchover time for new events is automatically scheduled within the maintenance window of the cluster.
2. In the dialog box that appears, set a periodic schedule and click Save.
On the Scheduled Events page, you can view event details. To modify an event's switchover time, select its cluster and click Schedule Time.
In the Schedule Time dialog box, set the Scheduled Switching Time and click OK.
Note
- Select the Set Earliest Execution Time check box to automatically use the earliest possible switchover time. After you click OK, the cluster prepares for the switchover and enters a pending state. If you clear this check box, you can customize the switchover time.
- The Scheduled Switching Time cannot be later than the Latest Start Time.

Causes and impacts of events

Type	Cause	Impact	Description
Hot upgrade Note Minor version updates for a cluster typically use a hot upgrade.	Cluster migration Note Scheduled maintenance due to host risks, expired hardware warranty, or operating system upgrades. The system migrates the cluster to a new server node. This applies to non-high-availability clusters and read-only clusters.	Transient connection interruption	During the switchover, the following impacts may occur: In most cases, a minor version update uses a hot upgrade. The cluster or the affected shard will experience a transient connection interruption and enter a read-only state for up to 30 seconds while data fully synchronizes. We recommend that you perform this operation during off-peak hours and ensure your application has a reconnection mechanism. Cluster access from DMS and DTS is temporarily disrupted. Service resumes automatically after the operation is complete. Note The operation occurs during the cluster's maintenance window that follows the scheduled switchover time.
	Primary/standby switchover Note Scheduled maintenance due to host risks, expired hardware warranty, or operating system upgrades. The system initiates a primary/standby switchover. This applies only to high-availability clusters.
	Cluster parameter adjustment Note Scheduled maintenance due to known parameter risks. The system modifies the parameters of the cluster. If the new parameters include parameters that require a cluster restart to take effect, the cluster is restarted.
	Host risk fixing Note This event fixes fault risks on the host where the cluster resides.
	Backup mode upgrade Note This upgrade switches the cluster's backup mode from logical backup to physical database and table backup to provide faster backup and recovery capabilities.
	Minor version update Note To improve user experience, PolarDB periodically releases minor versions of clusters to add features or fix known issues.	Transient connection interruption	During the switchover, the following impacts may occur: In most cases, a minor version update uses a hot upgrade. The cluster or the affected shard will experience a transient connection interruption and enter a read-only state for up to 30 seconds while data fully synchronizes. We recommend that you perform this operation during off-peak hours and ensure your application has a reconnection mechanism. Cluster access from DMS and DTS is temporarily disrupted. Service resumes automatically after the operation is complete. Note The operation occurs during the cluster's maintenance window that follows the scheduled switchover time.
		Differences between minor versions	Different minor versions (kernel versions) contain different updates. Review the differences between your current minor version and the new version. For more information, see Release notes of minor engine versions of PolarDB for MySQL.
	Proxy minor version update Note To improve user experience, PolarDB periodically releases minor versions of proxy nodes to add features or fix known issues.	Transient connection interruption	During the switchover, the following impacts may occur: In most cases, a minor version update uses a hot upgrade. The cluster or the affected shard will experience a transient connection interruption and enter a read-only state for up to 30 seconds while data fully synchronizes. We recommend that you perform this operation during off-peak hours and ensure your application has a reconnection mechanism. Cluster access from DMS and DTS is temporarily disrupted. Service resumes automatically after the operation is complete. Note The operation occurs during the cluster's maintenance window that follows the scheduled switchover time.
		Differences between minor versions	Different minor versions contain different updates. Review the differences between your current minor version and the new version.
	Network upgrade Note Upgrades network hardware to improve the network performance and stability of the cluster.	Transient connection interruption	During the switchover, the following impacts may occur: In most cases, a minor version update uses a hot upgrade. The cluster or the affected shard will experience a transient connection interruption and enter a read-only state for up to 30 seconds while data fully synchronizes. We recommend that you perform this operation during off-peak hours and ensure your application has a reconnection mechanism. Cluster access from DMS and DTS is temporarily disrupted. Service resumes automatically after the operation is complete. Note The operation occurs during the cluster's maintenance window that follows the scheduled switchover time.
		Impact on direct VIP connections	Some network upgrades may involve cross-availability-zone migration, which changes the cluster's virtual IP address (VIP). If your client connects to the database using the VIP, the connection will be interrupted. Note To avoid this impact, connect using the cluster's domain name and disable the DNS cache on your application and its server.
	Storage gateway upgrade Note Upgrades storage gateways to improve the storage performance and stability of the cluster.	I/O jitter	Temporary I/O jitter or increased SQL latency may occur. The impact lasts no more than 3 seconds.
Cold upgrade Note In special scenarios, such as a major version upgrade of a cluster from 8.0.1 to 8.0.2 or an upgrade from a public preview version to a GA version, a cold upgrade is required.	Major version upgrade	Brief cluster interruption	During the switchover, the following impacts may occur: The cluster or the affected shard typically experiences a connection interruption of less than 2 minutes. For clusters that have a large number of table files, have large transactions running before the upgrade, or have high CPU utilization before the upgrade, the interruption during a cold upgrade may exceed 2 minutes. We recommend that you perform this operation during off-peak hours and ensure your application has a reconnection mechanism. If a cold upgrade is required, review the differences between the versions and select a suitable upgrade time based on your business requirements. Note The operation occurs during the cluster's maintenance window that follows the scheduled switchover time. To ensure data security, we recommend that you back up your data before a major version upgrade or an upgrade from a public preview version.
	Public preview version upgrade	Brief cluster interruption

Related APIs

API	Description
DescribePendingMaintenanceActions	Returns the number of pending events for each task type.
ModifyPendingMaintenanceAction	Modifies the switchover time for a pending event.
DescribePendingMaintenanceAction	Returns the details of a pending event.