To enhance user experience and provide improved service performance and stability, Alibaba Cloud occasionally generates pending events to upgrade the hardware and software of specific servers or replace network facilities. For example, a pending event is generated when the minor version of databases needs to be updated. After you receive an event notification from Alibaba Cloud, you can check the impact of the event and change the scheduled time of the event to meet your business requirements.
Description of event types
Event types indicate the severity levels of pending events. The following event types are supported:
- Urgent patch: events such as high-risk vulnerability fixes
- System maintenance: events such as minor version updates
Precautions
You are notified of ApsaraDB for Redis pending events such as instance migrations or version upgrades at least three days before the events occur. Notifications for high-risk vulnerability fixes are sent three or fewer days before execution due to the urgency of these events. Event notifications are sent by usingphone calls, emails, internal messages, or the ApsaraDB for Redis console. To use this feature, log on to the Message Center console, enable ApsaraDB Fault or Maintenance Notifications, and then specify a contact. We recommend that you specify an O&M engineer as the contact.
Query and manage pending events
To learn the cause and impact of a pending event, find the relevant topic in the following table based on the type and engine of your instance. You can also handle the event based on your business requirements. For example, you can change the scheduled switchover time to a point in time during off-peak hours.
- If the system prompts that the scheduled switchover time is invalid, you can set the switchover time to a point in time within 30 days after the pending event is generated.
- To be notified of event updates at the earliest opportunity, such as new pending events and task progress, you can configure alert rules for pending events in the CloudMonitor console. For more information, see Subscribe to event notifications.
Causes and impacts of pending events
| Cause | Impact | Description |
|---|---|---|
| Instance migration | Transient connections | When the switchover is performed during the maintenance window after the scheduled switchover time, you may experience the following impacts:
|
| Switchover between master and replica nodes | ||
| Instance parameter adjustment | ||
| Host vulnerability fixing | ||
| SSL certificate update | ||
| Backup mode change | ||
| Zone migration | ||
| Minor version update | Transient connections | When the switchover is performed during the maintenance window after the scheduled switchover time, you may experience the following impacts:
|
| Differences between minor versions | Different minor versions or engine versions have different updates. You must take note of the differences between the current minor version and the minor version to which you want to update your instance. For more information, see the relevant release notes. Some services do not have available release notes for minor versions. Release notes are available only for the following services:
| |
| Proxy minor version update | Transient connections | When the switchover is performed during the maintenance window after the scheduled switchover time, you may experience the following impacts:
|
| Differences between minor versions | Different minor versions have different updates. You must take note of the differences between the current minor version and the minor version to which you want to update your instance. For more information, see the relevant release notes. Some services do not have proxy servers or available release notes for proxy servers. Release notes are available only for the following services:
| |
| Network upgrade | Transient connections | When the switchover is performed during the maintenance window after the scheduled switchover time, you may experience the following impacts:
|
| Change of virtual IP addresses | Some network upgrades may involve cross-zone migrations, which change the virtual IP address of an instance. If a client uses a virtual IP address to connect to a cloud database, the connection is interrupted. Note To prevent transient connections, you must use the endpoint in the form of a domain name that is provided by your instance and disable the DNS cache feature of the application and its server. | |
| Storage gateway upgrade | I/O jitter | Temporary I/O jitter may occur, and the SQL latency may increase. These impacts last no longer than 3 seconds. |