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Checking the status of your nodes

You can use the node status command to check the status of a target node in your HCP system. Any user can perform the node status command. System-level users with the administrator role can enable and disable the node status API.

The request to check the status of a node requires a URL specifying the front-end IP address of the target node. You enter the command in the following format:

http://node-front-end-ip-address/node_status 

You can also request node metrics to be returned with the node HTTP status return code. To request node metrics, you additionally need to:

  • Specify a type URL query parameter with a value of metrics.
  • Specify the format URL query parameter with a value of xml or json.

If you omit the format parameter, you are only returned a response status code.

Request-specific return codes (node status)

The following table describes the HTTP return status codes that can be returned from a node status request.

CodeHTTP statusDescription
204OKNode is configured to return node status
403Forbidden

The HCP node status check returns a 403 forbidden message for the following reasons:

  • The system administrator has not enabled node status through the System Management Console.
  • The HCP system does not have a load balancer or the system administrator has not added the load balancer IP address to the Security Console Allow list.
540 System is in Read Only mode
541 Node is not available

Response body (node status)

The following table describes the properties included in the node status metrics.

Property nameData typeDescription
httpConnectionsintegerThe number of HTTP connections.
cpuUserfloatThe percentage of CPU capacity used by HCP processes.
cpuSystemfloatThe percentage of CPU capacity used by the operating system kernel.
iowaitfloatThe percentage of CPU capacity spent waiting to access logical volumes that are in use by other processes.
swapoutfloat The average number of pages swapped out of memory per second.
idfloatThe volume name.
blocksReadfloatThe average number of blocks read from the logical volume per second.
blocksWritefloatThe average number of blocks written to the logical volume per second.
diskUtilizationfloatThe usage of the communication channel between the operating system and the logical volume as a percent of the channel bandwidth.
frontendBytesReadfloatThe average number of bytes read from the node per second over the front-end network.
frontendBytesWritefloat The average number of bytes written to the node per second over the front-end network.
backendBytesReadfloatThe average number of bytes read from the node per second over the back-end network.
backendBytesWritefloat The average number of bytes written to the node per second over the back-end network.
requestTimestampintegerThe exact time that the timestamp request was issued in milliseconds.
metricsTimestampintegerThe exact time that the metrics were collected in milliseconds.

Example: Retrieving node status

Here's a sample request that retrieves a return status code and node metrics for a node in the system. In this example, the target node IP address is 192.168.210.16 and the requested output format is JSON.

Request with cURL command line

curl -i http://192.168.210.16/node_status?type=metrics&format=json

Response headers

HTTP/1.1 200 OK

Response body in JSON
{
    "httpConnections" : "10000",
    "cpuUser" : "0.36",
    "cpuSystem" : "0.56",
    "iowait" : "0.05",
    "swapout" : "0.00",
    "volume" : [ {
        "id" : "archive034",
        "blocksRead" : "0.00",
        "blocksWrite" : "0.29",
        "diskUtilization" : "0.00"
    }, {
        "id" : "archive033",
        "blocksRead" : "0.00",
        "blocksWrite" : "0.59",
        "diskUtilization" : "0.00"
    } ],
    "frontendBytesRead" : "0.14",
    "frontendBytesWrite" : "0.00",
    "backendBytesRead" : "0.83",
    "backendBytesWrite" : "0.59",
    "requestTimestamp" : "1509726379318",
    "metricsTimestamp" : "1509726014000"
}

 

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