To successfully scale out instances, you must verify resource availability, which depends on resource inventory and constraints. For Elastic Compute Service (ECS) scaling groups, Auto Scaling automatically assesses resource availability by scaling strength. This topic describes how to check and enhance scaling strength for reliable scale-out operations.
Background information
What is scaling strength?
Scaling strength in Auto Scaling defines the number of available resource pools, with more pools enabling higher scalability.
What is a resource pool?
A scaling group's instance configuration source defines the template used for scale-out operations. This template specifies the zones and instance types, where each zone-instance type pair forms a resource pool. The total number of such combinations determines the number of resource pools.
What is an available resource pool?
Resource pools are not always available. Resource pools may be limited in scale-out scenarios due to inventory constraints or compatibility issues, such as the g6e instance family supporting only Enterprise SSDs (ESSDs). This can reduce actual available pools below theoretical capacity.
Scaling strength rules
Weak: 0–1 available resource pools.
Medium: 2–3 available resource pools.
Strong: 4+ available resource pools.
NoteScaling strength depends solely on the number of available resource pools. A higher scaling strength improves (but does not guarantee) scale-out success rates.
Prerequisites
The scaling strength feature is supported only by scaling groups of the ECS type.
Scaling strength depends on resource inventory and constraints. For example, the g6e instance family only supports ESSDs. To expand resource pools when you configure the instance configuration source, specify a broader configuration scope. For information about the constraints of instance types, see Overview of instance families.
Scaling strength can fluctuate over time due to factors like zone shutdowns, instance type retirements, and resource inventory changes. Adjust your configurations as needed to accommodate these variations.
Procedure
To view or adjust scaling strength, follow these steps:
Log on to the Auto Scaling console.
In the left-side navigation pane, click Scaling Groups.
In the top navigation bar, select a region.
Find the desired scaling group and move your pointer over the scaling strength icon.
The following figure indicates a Medium scaling strength.
(Optional) To increase scaling strength from Weak or Medium, adjust the level as prompted.
In the panel that appears, click View Scalability Details to check the scaling strength.
In the panel that appears, adjust the number of zones or instance types to improve it.
Change the number of zones:
Click Go to Adjust next to the tips for changing vSwitches.
In the Edit VPC dialog box, change the number of vSwitches and click OK. In the following example, one vSwitch is added.
Change the number of instance types:
Click Go to Adjust next to the tips for changing the instance types in the scaling configuration.
On the Change Instance Type page, change the number of instance types. You can select multiple instance types and click OK.
Execution result
Scaling strength increases from Medium to Strong after vSwitch addition.
