System events are used to record and notify cloud resource information, such as O&M task executions, resource exceptions, and resource status changes. You can use system events to obtain information about risks and anomalies of ENS resources. For example, a system event is generated when an instance expires, when an instance needs to be migrated due to underlying upgrades, or when an instance is restarted due to system maintenance. You can respond to and handle the system event at the earliest opportunity to prevent your business from being affected by ENS resource unavailability or performance damage. This topic summarizes the system events supported by ENS, including unexpected O&M events, security events, node cutover events, and elimination events. This topic also provides suggestions on how to handle the system events.
System events examples
All system events are critical. Respond to and handle them promptly to prevent business impact.
Event | Description | Customer-side handling suggestions | State | Applicable instance types |
Instance restart due to system error | Alibaba Cloud immediately sends this system event when it detects that an instance with a cloud disk has gone down due to an unexpected hardware or software failure on the underlying host. | We recommend that you wait until the instance is automatically restarted and then check whether the instance and applications work as expected. Important When the instance is being restarted, Alibaba Cloud migrates the instance to a healthy host. |
| x86 compute Heterogeneous VM |
Instance redeployment due to system error | Alibaba Cloud immediately sends this system event when it detects that an instance with local disks cannot be recovered from a breakdown caused by a hardware or software failure on the underlying host. | We recommend that you take one of the following actions in response to the event:
Important By default, the instance is redeployed in five days. If you redeploy an instance, data on the local disks is lost. |
| x86 compute Heterogeneous VM |
Node cutover | Alibaba Cloud immediately sends this system event when it receives a cutover notification from a point of presence (POP) provider or when Alibaba Cloud performs necessary operations on a POP. | We recommend that you learn about the Internet service providers (ISPs) affected by the cutover, the affected range, and the affected time period, and determine whether to switch business traffic based on business sensitivity. |
| All |
IP address alerting | Alibaba Cloud immediately sends this system event when it receives an IP address alert notification from a regulator. | We recommend investigating and addressing the threats identified in the notification as soon as possible. |
| All |
IP address blocking | Alibaba Cloud immediately sends this system event when it receives an IP address blocking notification from a regulator. | We recommend that you check the IP address and handle the issue in the notification at your earliest opportunity. Then, you can submit a ticket to apply for unblocking your IP address. |
| All |
Node network interruption | Alibaba Cloud immediately sends this system event when Cloud Monitor detects that the Internet connection of a point of presence (POP) is interrupted. | We recommend that you determine whether to switch business traffic based on business sensitivity. |
| All |
Severe impacts on disk performance | Alibaba Cloud immediately sends this system event when it detects that an I/O jam on a cloud disk attached to an instance severely affects disk performance and prevents normal read and write operations. | We recommend that you isolate reads and writes on the disk at the application layer or disassociate the instance from the associated Edge Load Balancer (ELB) instance. |
| Cloud disk instance |
Instance migration required for POP upgrade | Alibaba Cloud sends this event 15 to 30 days in advance when it plans to upgrade the underlying points of presence (POPs) and physical machines for some ENS instances. These instances must be migrated across POPs. | Select a suitable time to migrate the related Elastic Compute Service (ECS) instances immediately or at a scheduled time. Important After the scheduled time, the network and power of the original POP will be shut down. Your instances and data on the original POP will be deleted. |
| All (Lossless data migration is supported only for x86 compute instances) |
Instance restart required for system maintenance | Alibaba Cloud immediately sends this system event when it detects a critical, non-breakdown hardware or software anomaly on the underlying host of an instance with a cloud disk. This anomaly may affect the future runtime of the instance. | Respond to the restart event immediately or at a scheduled time. |
| x86 compute |
Instance redeployment required for system maintenance | Alibaba Cloud immediately sends this system event when it detects a critical, non-breakdown hardware or software anomaly on the underlying host of an instance with local disks. This anomaly may affect the future runtime of the instance. | Respond to the redeployment event immediately or at a scheduled time. Important Redeploying the instance causes data loss on local disks. |
| x86 compute |