Manage Policy

You can dynamically adjust the number of servers in an Auto-Scaling Group based on monitoring metrics. When the metric exceeds the threshold you set, the server count is adjusted. At that time, you can choose one of three methods to adjust the server count: increase or decrease by a specified number, increase or decrease by a specified percentage, or fix the server count to a given value. When servers are launched or terminated due to a policy, the monitoring metric, such as CPU utilization, may temporarily exceed the threshold registered in the policy. However, because this is a brief moment, a cooldown period is set to avoid treating it as an abnormal condition. You can add and manage policies for an Auto-Scaling Group created in the Samsung Cloud Platform Console.

Add Policy

You can add policies to an Auto-Scaling Group. To add a policy to an Auto-Scaling Group, follow these steps.

1. Click the All Services > Compute > Virtual Server menu. Navigate to the Service Home page of Virtual Server.

2. Click the Auto-Scaling Group menu. You will be taken to the Auto-Scaling Group List page.

3. Auto-Scaling Group List page, click the resource you want to view detailed information for. You will be taken to the Auto-Scaling Group Details page.

4. Click the Policy Tab. You will be taken to the Policy Tab page.

5. Click the Add Policy button. The Add Policy popup window opens.

   Category	Required	Detailed description
   Category	Required	Policy Category Scale In: return server count Scale Out: increase server count
   Policy Name	Required	Name for policy-specific categorization
   Execution conditions	Required	Conditions to execute the policy Statistic: How to calculate the Metric Type Average: Average of servers in the Auto-Scaling Group Min: Minimum value among servers in the Auto-Scaling Group Max: Maximum value among servers in the Auto-Scaling Group Metric Type: CPU Usage, Network In(bytes), Network Out(bytes), Network In(Packets), Network Out(Packets) Operator: >= > <= < Threshold: Threshold corresponding to the Metric Type Period: Continuous duration required to trigger the condition (the condition must be continuously satisfied for N minutes for the policy to execute)
   execution unit	Required	Policy execution method Policy Type: Select the type of policy to execute. Increase or decrease the number of servers by a specified count: Increase or decrease the server count to the Target Value Increase or decrease the number of servers by a specified ratio: Increase or decrease by the Target Value ratio Fix the number of servers to the entered value: Fix the server count according to the Target Value Target Value: The number or ratio to apply for the selected Policy Type
   cooldown	Required	The waiting time (seconds) when a server is started or terminated due to a policy The default is 300 seconds, and it can be set between a minimum of 60 seconds and a maximum of 3,600 seconds.

   Table. Add Policy Popup Items
   Reference

   Policy > Cooldown Settings

   • When a server is started or terminated due to a policy, it waits for the configured cooldown period. Temporarily, the monitoring metric CPU utilization may exceed the threshold defined in the policy. However, because this is a transient moment rather than a condition for adjusting the number of servers, it is not considered an abnormal situation, and the system waits by applying the cooldown time.
   guide

   Policy execution operates within the configured Min/Max server count range.

   • Even if you input values outside the Min/Max server count range—such as increasing, returning, or fixing the number of servers—it operates within the configured Min/Max server count.
   • Example: When the minimum number of servers is 3, even if you set the server count fixed to 1, the server count does not drop to 1 and remains at the minimum of 3.

6. Add Policy After entering the required values in the popup window, click the Confirm button. The added policy can be viewed in the Policy List.

Policy creation example

The following is an explanation of the policy example. Please refer to it when creating a policy.

Edit Policy

You can modify the policies of an Auto-Scaling Group. To modify the policies of an Auto-Scaling Group, follow these steps.

1. Click the All Services > Compute > Virtual Server menu. Navigate to the Service Home page of Virtual Server.

2. Click the Auto-Scaling Group menu. Navigate to the Auto-Scaling Group List page.

3. Auto-Scaling Group List page, click the resource to view detailed information. You will be taken to the Auto-Scaling Group Details page.

4. Click the Policy Tab. You will be taken to the Policy Tab page.

5. Click the More > Edit button for the policy you want to modify. The Policy Edit Popup opens.

   Category	Required	Detailed description
   Category	Required	Policy Classification Scale In: Return server count Scale Out: Increase server count
   Policy Name	Required	Name for policy-specific categorization
   Execution conditions	Required	Conditions to execute the policy Statistic: Method to calculate the Metric Type Average: Average of servers in the Auto-Scaling Group Min: Minimum value among servers in the Auto-Scaling Group Max: Maximum value among servers in the Auto-Scaling Group Metric Type: CPU Usage, Network In(bytes), Network Out(bytes), Network In(Packets), Network Out(Packets) Operator: >= > <= < Threshold: Threshold corresponding to the Metric Type Period: Continuous duration (in minutes) that triggers the execution condition
   execution unit	Required	Policy execution method Policy Type: Select the type of policy to execute. Increase or decrease the number of servers by a specified count: Increase or reduce the server count to the Target Value Increase or decrease the number of servers by a specified ratio: Increase or reduce by the Target Value ratio Fix the number of servers to the entered value: Fix the server count according to the Target Value Target Value: The number or ratio to execute the selected Policy Type
   Cool down	Required	The waiting time (seconds) when a server is started or terminated due to a policy The default is 300 seconds, and it can be set from a minimum of 1 second up to a maximum of 3,600 seconds

   Table. Policy edit popup items

6. Edit Policy In the popup window, after entering the required values, click the Confirm button.

Policy addition and modification constraints

When adding or modifying a policy, constraints exist based on the policy classification, execution conditions, and the scope of those conditions. Below is an example of constraints for the policy. Refer to the constraint examples to add or modify the policy.

Example 1 - Need to check for duplicate registration of policy classification/execution conditions

Policy classification (Scale Out or Scale In) and execution condition (Metric type) cannot be registered redundantly with the same values.

If a policy is registered as above, you cannot add a policy with the category (Scale Out) execution condition (Metric type=CPU Usage) or modify it to that condition.

Example 2 - Need to verify the execution condition range for execution conditions (Metric type) and execution conditions (Statistic) according to policy classification

When the policy type (Scale Out or Scale In) differs, duplicate registration of the execution condition range (Comparison operator + Threshold) is not allowed for the same execution condition (Metric type) and execution condition (Statistic).

If a policy is registered as shown above, you cannot add a policy as below or modify it under the following conditions.
If the average CPU Usage is 60% or higher, a Scale Out policy is already registered; therefore, registering a Scale In policy when the average CPU Usage is 60% or lower would duplicate the 60% execution condition and cannot be added.

Example 3 - Need to verify the execution condition range for execution conditions (Metric type) and execution conditions (Statistic) according to policy classification

When the policy classification (Scale Out or Scale In) differs, duplicate registration of the execution condition range (Comparison operator + Threshold) is not allowed for the same execution condition (Metric type) and execution condition (Statistic).

If a policy is registered as shown above, you cannot add a policy as below or modify it under the following conditions.
When the average CPU Usage is 10% or less, a Scale In policy is already registered; therefore, if the average CPU Usage is less than 60% / 60% or less / 10% or more / exceeds 9%, you cannot register a Scale Out policy because the execution condition ranges would overlap.

Example 4 - Execution conditions (Metric type) and execution conditions (Statistic) can be registered according to the execution condition range based on policy classification

If the policy type (Scale Out or Scale In) differs, you can register when the execution condition (Metric type) is the same but the execution condition (Statistic) is different, or when the execution condition range (Comparison operator + Threshold) does not overlap.

If a policy is already registered as shown above, you can add a policy as below or modify it with the following conditions. Registration is possible when the execution condition ranges do not overlap, or when the execution condition (Statistic) differs.

Delete Policy

You can delete a policy of an Auto-Scaling Group. To delete a policy of an Auto-Scaling Group, follow these steps.

1. Click the All Services > Compute > Virtual Server menu. Navigate to the Service Home page of Virtual Server.
2. Click the Auto-Scaling Group menu. Navigate to the Auto-Scaling Group List page.
3. Auto-Scaling Group List page: click the resource you want to view details for. You will be taken to the Auto-Scaling Group Details page.
4. Click the Policy Tab. You will be taken to the Policy Tab page.
5. Select the policy to delete and click the Delete button. The Policy Deletion Confirmation popup opens.
6. Policy Deletion Confirmation Check the popup window and click the Confirm button.