View CLB monitoring information - Server Load Balancer - Alibaba Cloud Documentation Center

Classic Load Balancer (CLB) integrates with CloudMonitor to expose real-time performance metrics for your instances and listeners. Use these metrics to diagnose request timeouts, identify throttling, and assess load capacity.

Three access methods are supported: the CLB console, CloudMonitor API operations, and SDKs.

Prerequisites

Before you begin, ensure that you have:

A CLB instance with at least one listener configured. See Add a TCP listener, Add a UDP listener, Add an HTTP listener, or Add an HTTPS listener

View monitoring data in the CLB console

Log on to the CLB console.
Log on to the CLB console.
In the top navigation bar, select the region where your CLB instance resides.
On the Instances page, find your CLB instance and open the monitoring panel using either method:
- Method 1: Click in the Monitoring column. In the Monitoring Information panel, select the Instances or Listeners tab.
- Method 2: Click the instance ID. On the Instance Details tab, click Monitoring, then select the Instances or Listeners tab.

On the Instances > Bandwidth/Traffic view, the panel header shows Processed Data, which counts both requests and responses.

Set Time to filter by time range. Turn on Auto Refresh to update the data every minute.

Available metrics

The following metrics are available for all listener types (Layer 4 and Layer 7).

Metric	Description
Traffic	Inbound Traffic: traffic volume received by the CLB instance.<br>Outbound Traffic: traffic volume sent from the CLB instance.
Packets	Inbound Packets: packets received per second.<br>Outbound Packets: packets sent per second.
Concurrent connections	Active Connections: TCP connections in the ESTABLISHED state. With persistent connections, a single connection can carry multiple file transfers simultaneously.<br>Inactive Connections: TCP connections not in the ESTABLISHED state. Run `netstat -an` on Windows or Linux to inspect these connections.<br>Maximum Concurrent Connections: total number of TCP connections.
New connections	Average number of new TCP connections established between clients and the CLB instance per statistical period.
Traffic dropped	Inbound Traffic Dropped: inbound traffic dropped per second.<br>Outbound Traffic Dropped: outbound traffic dropped per second.
Packets dropped	Inbound Packets Dropped: inbound packets dropped per second.<br>Outbound Packets Dropped: outbound packets dropped per second.
Connections dropped	Connections dropped per second.

The following metrics apply only to Layer 7 (HTTP/HTTPS) listeners.

Metric	Description
Layer 7 QPS	HTTP and HTTPS requests processed per second.
Layer 7 RT	Average response time of the CLB instance.
Layer 7 2XX/3XX/4XX/5XX/Other status codes	HTTP response codes returned by listeners.
Layer 7 upstream code 4XX/5XX	HTTP response codes returned by backend servers.
Layer 7 upstream RT	Average response time of backend servers.

Query monitoring data using the API

CLB monitoring data is available through CloudMonitor API operations. The workflow consists of three steps: look up the CLB namespace, optionally list available metrics, then query the data.

Step 1: Get the CLB namespace using DescribeProjectMeta

Call DescribeProjectMeta to retrieve the CLB namespace in CloudMonitor.

Open OpenAPI Explorer for DescribeProjectMeta.

Set Labels to [{"name":"product","value":"SLB"}] and leave all other parameters at their defaults.

Sample request

http(s)://[Endpoint]/?Action=DescribeProjectMeta
&Labels=[{"name":"product","value":"SLB"}]
&<Common request parameters>

The response returns acs_slb_dashboard as the Namespace value. Use this namespace in subsequent API calls.

Sample response

{
    "PageSize": 30,
    "RequestId": "75B895A2-62A4-411E-871C-0EED97CC0D26",
    "PageNumber": 1,
    "Total": 1,
    "Resources": {
        "Resource": [
            {
                "Description": "Server Load Balancer",
                "Labels": "[{\"name\":\"product\",\"value\":\"SLB\"},{\"name\":\"productCategory\",\"value\":\"slb\"},{\"name\":\"groupFlag\",\"value\":\"true\"},{\"name\":\"cnName\",\"value\":\"CLB\"},{\"name\":\"enName\",\"value\":\"Server Load Balancer\"}]",
                "Namespace": "acs_slb_dashboard"
            }
        ]
    },
    "Code": 200,
    "Success": true
}

Step 2: (Optional) List available metrics using DescribeMetricMetaList

Call DescribeMetricMetaList to see all time series metrics available for CLB, or consult CLB monitoring metrics directly.

Open OpenAPI Explorer for DescribeMetricMetaList.

Set Namespace to acs_slb_dashboard and leave all other parameters at their defaults.

Sample request

http(s)://[Endpoint]/?Action=DescribeMetricMetaList
&Namespace=acs_slb_dashboard
&<Common request parameters>

The response lists all CLB metrics with their dimensions, units, and supported statistics. Confirm that InstanceQps (Layer 7 QPS) is present before using it in the next step.

Sample response

{
    "TotalCount": 53,
    "RequestId": "789846B4-56FC-4681-998C-5B7DBDFBE28F",
    "Resources": {
        "Resource": [
            {
                "MetricName": "ActiveConnection",
                "Periods": "60,300",
                "Description": "Active connections on the port",
                "Dimensions": "userId,instanceId,port,protocol",
                "Labels": "[{\"name\":\"alertUnit\",\"value\":\"Count\"},{\"name\":\"minAlertPeriod\",\"value\":\"60\"},{\"name\":\"metricCategory\",\"value\":\"port\"},{\"name\":\"is_alarm\",\"value\":\"true\"}]",
                "Unit": "Count",
                "Statistics": "Average,Minimum,Maximum",
                "Namespace": "acs_slb_dashboard"
            },
            {
                "MetricName": "DropConnection",
                "Periods": "60,300",
                "Description": "",
                "Dimensions": "userId,instanceId,port,protocol",
                "Labels": "[{\"name\":\"alertUnit\",\"value\":\"Count/Second\"},{\"name\":\"minAlertPeriod\",\"value\":\"60\"},{\"name\":\"metricCategory\",\"value\":\"port\"},{\"name\":\"is_alarm\",\"value\":\"true\"}]",
                "Unit": "Count/s",
                "Statistics": "Average,Minimum,Maximum",
                "Namespace": "acs_slb_dashboard"
            }
        ]
    },
    "Code": 200,
    "Success": true
}

Step 3: Query metric data

Use one of the following operations depending on what you need:

DescribeMetricLast — returns the most recent data point for a metric
DescribeMetricList — returns data points within a time range
Fine-grained Monitoring
CLB metric reference
CLB metric reference

Query the latest data using DescribeMetricLast

Call DescribeMetricLast to get the latest value of a metric. This example queries Layer 7 QPS (InstanceQps).

Open OpenAPI Explorer for DescribeMetricLast.Log on to OpenAPI Explorer
Set the following parameters and leave all others at their defaults:
Sample request
```
http(s)://[Endpoint]/?Action=DescribeMetricLast
&MetricName=InstanceQps
&Namespace=acs_slb_dashboard
&Dimensions=[{"instanceId":"lb-bp1r92vzpemy099f******"}]
&<Common request parameters>
```
Parameter Value
MetricName InstanceQps
Namespace acs_slb_dashboard
Dimensions [{"instanceId":"lb-bp1r92vzpemy099f******"}]

Parameter	Value
MetricName	`InstanceQps`
Namespace	`acs_slb_dashboard`
Dimensions	`[{"instanceId":"lb-bp1r92vzpemy099f******"}]`

The response contains the latest QPS data in the Datapoints field.

Sample response

{
    "RequestId": "DFF0A853-0E37-4108-A9AF-5B3D609BD489",
    "Period": "60",
    "Datapoints": "[{\"timestamp\":1585325460000,\"userId\":\"168840159596****\",\"instanceId\":\"lb-bp1r92vzpemy099f******\",\"port\":\"80\",\"protocol\":\"http\",\"vip\":\"121.43.**.**\",\"Average\":0}]",
    "Code": "200",
    "Success": true
}

Query historical data using DescribeMetricList

Call DescribeMetricList to retrieve data points for a metric within a specific time window. This example queries Layer 7 QPS (InstanceQps).

Open OpenAPI Explorer for DescribeMetricList.
Set the following parameters and leave all others at their defaults: StartTime and EndTime accept two formats:
Sample request
```
http(s)://[Endpoint]/?Action=DescribeMetricList
&MetricName=InstanceQps
&Namespace=acs_slb_dashboard
&Dimensions=[{"instanceId":"lb-bp1r92vzpemy099f******"}]
&StartTime=2020-03-28 00:10:00
&EndTime=2020-03-28 00:11:00
&<Common request parameters>
```
- UNIX timestamp (milliseconds since January 1, 1970, 00:00:00 UTC)
- UTC time in YYYY-MM-DDThh:mm:ssZ format
Parameter Value
MetricName InstanceQps
Namespace acs_slb_dashboard
Dimensions [{"instanceId":"lb-bp1r92vzpemy099f******"}]
StartTime 2020-03-28 00:10:00
EndTime 2020-03-28 00:11:00

Parameter	Value
MetricName	`InstanceQps`
Namespace	`acs_slb_dashboard`
Dimensions	`[{"instanceId":"lb-bp1r92vzpemy099f******"}]`
StartTime	`2020-03-28 00:10:00`
EndTime	`2020-03-28 00:11:00`

The response returns all data points in the specified window.

Sample response

{
    "RequestId": "DFF0A853-0E37-4108-A9AF-5B3D609BD489",
    "Period": "60",
    "Datapoints": "[{\"timestamp\":1585325460000,\"userId\":\"168840159596****\",\"instanceId\":\"lb-bp1r92vzpemy099f******\",\"port\":\"80\",\"protocol\":\"http\",\"vip\":\"121.43.**.**\",\"Average\":0}]",
    "Code": "200",
    "Success": true
}

View monitoring data using SDKs

OpenAPI Explorer generates ready-to-use SDK code for any CloudMonitor operation. This example queries the maximum number of concurrent connections (InstanceMaxConnection) for a CLB instance using DescribeMetricList.

Open OpenAPI Explorer for DescribeMetricList.
Set the following parameters and leave all others at their defaults:
Parameter Value
MetricName InstanceMaxConnection
Namespace acs_slb_dashboard
Dimensions [{"instanceId":"lb-bp1r92vzpemy099f******"}]
StartTime 2022-10-13 20:45:03
EndTime 2022-10-13 20:47:03
Click the SDK Sample Code tab and select Python.
Click Example to generate and run the code. The results appear in the panel below.

Parameter	Value
MetricName	`InstanceMaxConnection`
Namespace	`acs_slb_dashboard`
Dimensions	`[{"instanceId":"lb-bp1r92vzpemy099f******"}]`
StartTime	`2022-10-13 20:45:03`
EndTime	`2022-10-13 20:47:03`

What's next

For a complete list of CLB monitoring metrics and their descriptions, see CLB monitoring metrics.

For definitions of CLB monitoring metrics, see CLB metric reference.