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Assess resource availability with scaling strength

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To prevent scale-out failures due to insufficient resource inventory, use the scaling strength metric to evaluate the health of your resource pools. By diversifying your configuration with multiple zones and alternative instance types, you can improve scale-out success and ensure service stability.

Key concepts

Elastic strength is a core metric that measures the scaling capability of an ECS-type scaling group. It assesses the likelihood of successful scale-outs by evaluating the inventory health score of each resource pool.

  • Resource pool

    A scaling group's resource pool consists of a combination of specified zones and instance types. During a scale-out event, the scaling group creates new instances from these resource pools based on predefined rules. The diversity and health of your resource pools directly determine the scale-out success rate.

    Important

    Not all resource pools are available during scale-out events

    During a scale-out event, the scaling group filters available resource pools based on constraints in the scaling configuration (for example, some instance types do not support ESSDs) and then creates instances from the filtered pools.

  • Inventory health score

    The inventory health score evaluates the supply stability of a single resource pool. It is a composite score based on three dimensions: current inventory sufficiency, future replenishment capability, and resource popularity. A higher score indicates a more reliable resource supply.

    • 5–6 points (High certainty): The resource supply is sufficient, and the scale-out success rate is high.

    • 1–4 points (Uncertain supply): The resource supply is uncertain. We recommend adding or changing your resource pool configuration, for example, by adding vSwitches in other zones or alternative instance types.

    • -3–0 points (Supply warning): The resource supply is low, and there is a high risk of scale-out failure. We strongly recommend that you adjust your configuration.

View scaling strength

Follow these steps to view and adjust the scaling strength.

  1. Log on to the Auto Scaling console.

  2. In the navigation pane on the left, click Scaling Groups.

  3. In the top navigation bar, select a region.

  4. Find the scaling group and check its scaling strength.

    The scaling strength is displayed for the scaling group in the list.

  5. Click the scaling strength icon to view the inventory health score for each combination of Instance Type and vSwitch. Click a specific score to view calculation details.

    In the scaling strength details dialog box, a table displays columns for Instance Type, Zone, vSwitch List, Status, and Inventory Health. A tip at the top suggests improving the scaling strength by selecting vSwitches in different zones for the scaling group.

Best practices

  • Improve scaling strength with resource diversity

    Avoid relying on a single resource pool. The more diverse your resource configuration, the more easily a scaling group can find an alternative if a specific resource is unavailable. You can increase the number of resource pools and expand your fallback options by using the following methods:

    • Configure multiple zones: When creating a scaling group, associate vSwitches from at least two zones. If resources are constrained in one zone, Auto Scaling automatically attempts to create an instance in another zone.

    • Add alternative instance types: Do not configure only one instance type. Add multiple alternative instance types to your scaling configuration. This allows the system to create an instance of a different type if one type has insufficient inventory.

  • Continuously monitor and optimize scaling strength

    Scaling strength is a dynamic metric. A one-time "perfect" configuration does not guarantee long-term effectiveness.

    For example, scaling strength can decrease due to zone decommissioning, instance type retirement, or changes in inventory capacity.

    Therefore, incorporate the evaluation and optimization of scaling strength into your regular operations and maintenance (O&M) procedures. Before major events or business promotions, perform a comprehensive assessment and optimization of all critical scaling groups. This ensures your system can scale out at the most critical moments, ensuring business stability.

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