RebalanceInstances

Description

To rebalance the distribution of ECS instances in a multiple-zone scaling group, Auto Scaling creates new ECS instances to replace existing ones. Auto Scaling starts new instances before it terminates the existing instances. This ensures that the performance and availability of your applications are not affected.

• You can call this operation only when you set the MultiAZPolicy parameter of the multi-zone scaling group to BALANCE.
• You can perform rebalancing only when the distribution of ECS instances in a scaling group is significantly imbalanced.
• A maximum of 20 ECS instances can be replaced in one rebalancing activity.
• If the number of ECS instances in the scaling group is about to reach or reaches the maximum number of instances specified by the MaxSize parameter during a rebalancing activity and you must continue with the rebalancing activity, Auto Scaling allows the number of ECS instances in the scaling group to temporarily exceed the value of MaxSize. The excess number of instances ranges from one to 10% of the value of MaxSize. The exceeding status lasts until the rebalancing activity ends, typically for 1 to 6 minutes.

Request parameters

Response parameters

Examples

Sample requests

https://ess.aliyuncs.com/?Action=RebalanceInstances
&ScalingGroupId=asg-bp18p2yfxow2dloq****
&<Common request parameters>

Sample success responses

XML format

<RebalanceInstancesResponse>
      <RequestId>473469C7-AA6F-4DC5-B3DB-A3DC0DE3C83E</RequestId>
      <ScalingActivityId>asa-kjgffgdfadah****</ScalingActivityId>
</RebalanceInstancesResponse>

JSON format

{
    "RequestId": "473469C7-AA6F-4DC5-B3DB-A3DC0DE3C83E",
    "ScalingActivityId": "asa-kjgffgdfadah****"
}

Error codes

For a list of error codes, visit the API Error Center.