By using Tencent Cloud Cloud Monitoring, you can retrieve statistical data based on an ordered set of time series data (called metrics). You can use these metrics to verify whether your system is running as expected. If the thresholds are reached, scaling will be triggered.
AS monitoring metrics
AS currently supports the following metrics:
CPU utilization
Memory utilization
Private network bandwidth in
Public network bandwidth in
Private network bandwidth out
Public network bandwidth out
TCP established connection count
Each metric supports the following values:
Maximum value
Minimum value
Average value
Metrics aggregation method
Tencent Cloud Auto Scaling monitors CVM clusters, and collects multiple monitoring metrics for multiple CVMs across multiple time periods. This data is aggregated and used to inform operations based on the policies that you configure.
It collects one sample per minute for each of CVM based on the set monitoring items. If the sample value meets the configured rules for multiple periods consecutively (the number of periods can be customized), the alarm scaling activity will be triggered.
For example: A scaling group has 5 CVM instances and the defined alarm scaling policy is “Maximum/minimum/average CPU utilization of more than 50% within a 5 minutes period for 3 times consecutively.” Auto Scaling collects the data and determines whether the policy for the alarm scaling rule is met. The steps are as follows:
1. Collects one value from each CVM per minute. In one sampling period (the current period is 5 minutes) it takes 25 CPU utilization values.
2. According to the configured maximum/minimum/average values, it determines whether the policy for the alarm scaling rule is met.
Maximum value: If the maximum value in these 25 values exceeds the threshold (50%), this period meets the alarm scaling rule.
Minimum value: If the minimum value in these 25 values exceeds the threshold (50%), this period meets the alarm scaling rule.
Average value: If the average value of these 25 values exceeds the threshold (50%), this period meets the alarm scaling rule.
3. If the rule is met for 3 consecutive periods (a total of 15 minutes, with each 5-minute period considered the current period), the scaling action is triggered.