Citrix Web HTTP Response Status Test

Like the HTTP request methods, one/more HTTP response status messages may also consume considerable bandwidth, thus increasing the bandwidth usage of the NetScaler appliances managing the web traffic. To identify such bandwith-intensive response statuses, use this test.

Target of the test : An AppFlow-enabled NetScaler Appliance

Agent deploying the test : A remote agent

Outputs of the test : One set of results for every HTTP response status

Configurable parameters for the test
Parameter Description

Test period

How often should the test be executed. It is recommended that you set the test period to 5 minutes. This is because, the eG AppFlow Collector is capable of capturing and aggregating AppFlow data related to the last 5 minutes only.

Host

The host for which the test is to be configured.

Cluster IPs

This parameter applies only if the NetScaler appliance being monitored is part of a NetScaler cluster. In this case, configure this parameter with a comma-separated list of IP addresses of all other nodes in that cluster.

If the monitored NetScaler appliance is down/unreachable, then the eG AppFlow Collector uses the Cluster IPs configuration to figure out which other node in the cluster it should connect to for pulling AppFlow statistics. Typically, the collector attempts to connect to every IP address that is configured against Cluster IPs, in the same sequence in which they are specified. Metrics are pulled from the first cluster node that the collector successfully establishes a connection with.

Enable Logs

This flag is set to No by default. This means that, by default, the eG agent does not create AppFlow logs. You can set this flag to Yes to enable AppFlow logging. If this is done, then the eG agent automatically writes the raw AppFlow records it reads from the collector into individual CSV files. These CSV files are stored in the <EG_AGENT_INSTALL_DIR>\NetFlow\data\<IP_of_Monitored_NetScaler>\webappflow\actual_csv folder on the eG agent host. These CSV files provide administrators with granular insights into the web appflows, thereby enabling effective troubleshooting.

Note:

By default, the eG agent creates a maximum of 10 CSV files in the actual_csv folder. Beyond this point, the older CSV files will be automatically deleted by the eG agent to accommodate new files with current data. Likewise, a single CSV file can by default contain a maximum of 99999 records only. If the records to be written exceed this default value, then the eG agent automatically creates another CSV file to write the data.

If required, you can overwrite these default settings. For this, do the following:

  1. Login to the eG agent host.
  2. Edit the Netflow.Properties file in the <EG_AGENT_INSTALL_DIR>\NetFlow\config directory.
  3. In the file, look for the parameter, csv_file_retention_count.
  4. This is the parameter that governs the maximum number of CSV files that can be created in the auto_csv folder. By default, this parameter is set to 10. If you want to retain more number of CSV files at any given point in time, you can increase the value of this parameter. If you want to retain only a few CSV files, then decrease the value of this parameter.
  5. Next, look for the parameter, csv_max_flow_record_per_file.
  6. This is the parameter that governs the number of flow records that can be written to a single CSV. By default, this parameter is set to 99999. If you want a single file to accommodate more records, so that the creation of new CSVs is delayed, then increase the value of this parameter. On the other hand, if you want to reduce the capacity of a CSV file, so that new CSVs are quickly created, then decrease the value of this parameter.
  7. Finally, save the file.

Show Top N in DD

By default, this flag is set to Yes. This indicates that the detailed diagnosis of this test will display the details of only the top responses (in terms of the number of hits or bandwidth usage), by default. If you set this flag to No, then detailed diagnosis will provide the details of all responses processed by the monitored NetScaler appliance for the web applications it manages.

Sort DD Data By

By default, this test sorts the detailed diagnostics it reports in the descending order of the count of HTTP responses of a type (i.e., response code) from a web application. Accordingly, the Hits option is by default chosen against this parameter. Detailed diagnosis so sorted will point you to web applications that sent too many error responses, so you can investigate why the web applications sent such responses. If required, you can sort the detailed diagnostics in the descending order of bandwidth usage, so you can quickly identify those web applications that have been sending out bandwidth-intensive responses to users. For this, choose the Bandwidth option against this parameter.

Top N DD Limit

This parameter applies only if the Show Top N in DD flag is set to 'Yes'.

By default, this parameter is set to 10, indicating that the detailed diagnostics will report the top-10 HTTP responses by default. You can change the 'N' in Top N by specifying any number of your choice in this text box.

DD Frequency

Refers to the frequency with which detailed diagnosis measures are to be generated for this test. The default is 1:1. This indicates that, by default, detailed measures will be generated every time this test runs, and also every time the test detects a problem. You can modify this frequency, if you so desire. Also, if you intend to disable the detailed diagnosis capability for this test, you can do so by specifying none against DD Frequency.

Detailed Diagnosis

To make diagnosis more efficient and accurate, the eG Enterprise suite embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option.

The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled:

  • The eG manager license should allow the detailed diagnosis capability
  • Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Hits

Indicates the number of responses of this status sent by this NetScaler appliance.

Number

Compare the value of this measure across statuses to know which response is received often.

Use the detailed diagnosis of this measure to know which application is sending out the maximum number of error responses and/or which application is sending out bandwidth-intensive responses.

Bandwidth

Indicates the total size of the responses of this status sent by this appliance.

KB

Compare the value of this measure across statuses to know which type of responses is consuming bandwidth excessively.

Avg render time

Indicates the elapsed time, from when the browser starts to receive the first byte of a response of this type until either all page content has been rendered or the page load action has timed out.

Msecs

Compare the value of this measure across response types to know which type of response is delaying page rendering.

For a specific response type, the detailed diagnosis of the Hits measure reveals the web applications that sent out HTTP responses of that type, and the URLs for which the applications sent out such responses. The count of the responses of that type and average bandwidth usage of the responses is also reported, so you can quickly identify the web applications and request URLs that returned the maximum number of error responses and bandwidth-intensive responses. The details of the client to which such responses were sent will also be reported as part of detailed diagnostics.

Figure 1 : The detailed diagnosis of the Hits measure reported by the Citrix Web HTTP Response Status test