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sol12174: Comparing the running configuration with the saved configuration
How-ToHow-To

Original Publication Date: 10/26/2010
Updated Date: 03/29/2012

Overview of the BIG-IP system running and saved configurations

The running configuration is the configuration that the BIG-IP system has loaded into memory and is currently using to process traffic. The saved configuration is the configuration that the BIG-IP system has most recently written to disk. The saved configuration consists, for example, of the /config/bigip_base.conf and /config/bigip.conf files.

When you make a configuration change to the BIG-IP system, the saved configuration is not always automatically updated to reflect the change. Whether or not this happens depends on the configuration method that you are using:

  • When you use the Configuration utility, changes take effect immediately and are also saved to disk immediately.
  • When you use the bigpipe or tmsh utility, changes take effect immediately, but are not automatically saved to disk. If the new configuration is working as intended and you want to keep the changes, you must manually save the configuration to disk (for example, by entering the bigpipe save all command). If you want to discard the changes, you must reload the saved configuration (for example, by entering the bigpipe load command).
  • When you manually edit a configuration file (for example, the /config/bigip.conf file), changes will not take effect until you reload the configuration from disk (for example, by entering the bigpipe load command). If you write the configuration to disk before reloading it, the changes you made to the configuration file will be lost.

From the above bullet points, the running and saved configurations may not always match. In certain cases, a mismatch may also be indication of an issue. While there is no easy way to compare the two configurations side-by-side, you may be able to get an indication of whether they are the same by counting the number of virtual servers present in each configuration.

This technique consists of counting the number of virtual servers present in the running configuration and comparing this value with the number of virtual servers present in the saved configuration. If the two numbers do not match, the running configuration and the saved configuration are not the same.

Note: By counting the number of virtual servers, you will not be able to ascertain whether the running and saved configurations are identical; this test will only indicate whether the running and saved configurations are likely to be the same or definitely not the same.

Note: This test is not indicative on BIG-IP GTM systems, as the only virtual server objects present in their configuration are the Listeners.

Comparing the virtual server counts

You can determine the number of virtual servers present in each configuration by performing the following procedure:

  1. Log on to the BIG-IP system command line.
  2. To determine how many virtual servers are present in the running configuration, enter the following command:

    bigpipe virtual list | egrep '^virtual [^ ]* {' | wc -l

    This command will only return a number, for example:

    # bigpipe virtual list | egrep '^virtual [^ ]* {' | wc -l
    31
  3. To determine how many virtual servers are present in the saved configuration, enter the following command:

    cat /config/bigip.conf /config/bigip_local.conf | egrep '^virtual [^ ]* {' | wc -l

    This command will only return a number, for example:

    # cat /config/bigip.conf /config/bigip_local.conf | egrep '^virtual [^ ]* {' | wc -l
    31
  4. Once you have determined how many virtual servers are present in each configuration, compare the two values:
    • If the number of virtual servers in the running configuration is the same as the number of virtual servers in the saved configuration, this usually indicates that the BIG-IP system has successfully loaded the complete configuration into memory. As a further test, you may run the bigpipe verify load command from the command line to determine whether the saved configuration compiles without errors.

      Note: The bigpipe verify load command verifies the saved configuration but does not load it. You can safely run this command at any time; the running configuration will not be modified.
    • If the number of virtual servers in the saved configuration is greater than the number of virtual servers in the running configuration, this may indicate the following:
       
      • The configuration has not fully loaded because you have manually edited one of the configuration files and introduced a syntax error.
      • The configuration has not fully loaded because you have recently upgraded the BIG-IP system and the configuration you have rolled forward is no longer valid in the new software version.
      • You have added one or more virtual servers by manually editing the configuration files but you have not reloaded the configuration yet.
      • You have deleted one or more virtual servers from the running configuration using the bigpipe or tmsh utility but you have not saved the changes to disk yet.
      To correct this situation, run the bigpipe verify load command from the command line. If an error is returned, the error is usually self-explanatory and should provide enough information to allow you to fix the invalid configuration file. If no  error is returned, determine which configuration you want to keep, and then either restore the saved configuration (by entering the bigpipe load command) or save the running configuration to disk (by entering the bigpipe save all command).
    • If the number of virtual servers in the running configuration is greater than the number of virtual servers in the saved configuration, this usually indicates that you have added one or more virtual servers to the running configuration using the bigpipe or tmsh utility; however, you have not saved the changes to disk yet. If the new configuration is working as intended, you can save the running configuration to disk by entering the bigpipe save all command. Instead, if you want to restore the saved configuration, enter the bigpipe load command.

    Note: This test does not cover all possible scenarios. For example, if one virtual server fails to load because of a syntax error in the /config/bigip.conf file, the number of virtual servers in the saved configuration should be greater than the number of virtual servers in the running configuration by 1. However, if in the above example you create a new virtual server using the bigpipe or tmsh utility before you count the virtual servers, the number of virtual servers in the running and saved configurations will appear to match. In this case, it is not apparent that one virtual server has failed to load.

    Note: This test is also automatically performed by iHealth Diagnostic H754819 when you upload a BIG-IP version 10.x qkview to the iHealth website.

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