Auto Scaling:RebalanceInstances

Description

To rebalance ECS instances in a multiple-zone scaling group, Auto Scaling creates ECS instances to replace the existing instances. Auto Scaling starts the created 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 if you set the MultiAZPolicy parameter of the multi-zone scaling group to BALANCE.
• You can rebalance ECS instances in a scaling group only when the distribution of ECS instances in the scaling group is significantly imbalanced.
• You can replace up to 20 ECS instances during a rebalancing activity.
• If the number of ECS instances in the scaling group approaches or reaches the maximum number of instances that is specified by the MaxSize parameter during a rebalancing activity and the rebalancing activity must continue, Auto Scaling allows the number of ECS instances in the scaling group to temporarily exceed the maximum number. The excess number of instances ranges from one to 10% of the value of the MaxSize parameter. In most cases, Auto Scaling requires one to six minutes to rebalance the instances in the scaling group when the number of instances in the scaling group exceeds the maximum number.

Request parameters

Response parameters

Examples

Sample requests

http(s)://ess.aliyuncs.com/?Action=RebalanceInstances
&ScalingGroupId=asg-bp18p2yfxow2dloq****
&RegionId=cn-hangzhou
&<Common request parameters>

Sample success responses

XML format

HTTP/1.1 200 OK
Content-Type:application/xml

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

JSON format

HTTP/1.1 200 OK
Content-Type:application/json

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

Error codes

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