After a scaling activity completes, view its details to find out why it was triggered and how instance counts changed. This helps you audit scaling behavior, diagnose unexpected scale-outs or scale-ins, and investigate failures or warnings.
Scaling activity states
Each scaling activity ends in one of five states:
| State | Description |
|---|---|
| Reject | The scaling activity was rejected before execution. |
| In Progress | The scaling activity is in progress. |
| Success | All requested instances were added or removed. |
| Warning | The scale-out completed partially. Some instances were rolled back. See Warning state below. |
| Failed | The scaling activity failed to execute. |
For the full state reference, see Status.
What the details page shows
The scaling activity details page contains two categories of information:
| Category | What it tells you |
|---|---|
| Trigger cause | Which scheduled task, event-triggered task, or scaling rule initiated the activity |
| Execution result | The total number of Elastic Compute Service (ECS) instances in the scaling group after the activity completes |
Warning state
If a scale-out adds only some of the requested ECS instances, Auto Scaling rolls back the instances that failed to be added and marks the activity as Warning. For more information, see ECS instance rollback.
View scaling activity details
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Log on to the Auto Scaling console.
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In the left-side navigation pane, click Scaling Groups.
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In the top navigation bar, select the region where Auto Scaling is activated.
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Go to the scaling group details page using one of the following methods:
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Click the ID of the scaling group in the Scaling Group Name/ID column.
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Click Details in the Actions column.
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Click the Scaling Activities tab.
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Find the scaling activity and click its ID in the Scaling Activity ID column.
The details page shows the activity status, trigger cause, and the total number of instances in the scaling group after the activity completes.
