How to process messages from an orphan disk-buffer file using a separate syslog-ng OSE instance

Purpose

This section describes how to read messages from an orphan disk-buffer file by using a separate AxoSyslog process running parallel to the already running AxoSyslog instance.

Orphan disk-buffer files

In certain situations (for example, after modifying the disk-buffer configuration or losing the persist information), AxoSyslog creates a new disk-buffer file instead of using the already existing one. In these situations, the already existing disk-buffer file becomes a so-called orphan disk-buffer file.

Processing the messages from an orphan disk-buffer file by using a separate AxoSyslog instance

When AxoSyslog creates orphan disk-buffer files, you can start a separate AxoSyslog instance parallel to the AxoSyslog instance already running, and use the following resolution process to process the messages in the orphan disk-buffer file.

To process the messages from an orphan disk-buffer file using a separate AxoSyslog instance,

1. Identify the orphan disk-buffer files and make a record of them. For more information, see How to get information about disk-buffer files.

   It is important to know the type of the disk-buffer file. Disk-buffer file types can be normal (.qf) or reliable (.rqf).

   In the examples during this process, the /opt/syslog-ng/var/syslog-ng-00005.rqf orphan reliable disk-buffer file is used.

2. Determine the destination of the logs. The content of the disk-buffer may help you determine the logs’ destination. For more information, see How to get information about disk-buffer files.

   In the examples during this process, the destination 10.21.10.20 is used with the standard network() port 514.

3. Create a directory for the temporary instance. In the examples during this process, the /tmp/qdisk directory is used.

       mkdir /tmp/qdisk
   

   Warning

   Make sure that there is sufficient disk space in the directory. The minimum recommended disk space in the directory is equal to the size of the orphan disk-buffer file.

4. Create the configuration file /tmp/qdisk/qdisk.conf for the temporary instance with the following content.

   Example: creating the /tmp/qdisk/qdisk.conf configuration file for the temporary instance

       @version:7.0
       @include "scl.conf"
   
       options {
         keep-hostname(yes);
         keep-timestamp(yes);
       };
   
       destination d_destination {
       #    ADD YOUR DESTINATION HERE
   
       };
   
       log {
         destination(d_destination);
       };
   

5. Add your destination statement with disk-buffer() to the configuration file. You can copy the destination statement from your running AxoSyslog configuration.

   Warning

   Add the dir() option and set the disk-buffer file’s destination directory to the temporary directory (that is, /tmp/qdisk) in your destination statement.

6. Start the temporary AxoSyslog instance in the foreground.

       syslog-ng -Fe -f /tmp/qdisk/qdisk.conf -R /tmp/qdisk/qdisk.persist -c /tmp/qdisk/qdisk.ctl
   

   The AxoSyslog application will log to the console, so you will see any potential error that may occur during startup.

   The following example output displays that an empty disk-buffer file has been created and the connection to the remote destination has been established.

   Example: output displaying newly created empty disk-buffer file and connection established to remote destination

       Follow-mode file source not found, deferring open; filename='/no_such_file_or.dir'
       Reliable disk-buffer state saved; filename='/tmp/qdisk/syslog-ng-00000.rqf', qdisk_length='0'
       No server license found, running in client mode;
       syslog-ng starting up; version='7.0.20', cfg-fingerprint='eaa03b9efb88b87d7c1b0ce7efd042ed8ac0c013', cfg-nonce-ndx='0', cfg-signature='c0327a7f7e6418ce0399a75089377dfb662bb072'
       FIPS information; FIPS-mode='disabled'
       Syslog connection established; fd='7', server='AF_INET(10.21.10.20:514)', local='AF_INET(0.0.0.0:0)'
   

7. To stop AxoSyslog, press CTRL+C.

8. Overwrite the empty disk-buffer file with the orphan disk-buffer file.

       mv /opt/syslog-ng/var/syslog-ng-00005.rqf /tmp/qdisk/syslog-ng-00000.rqf
   

9. Start AxoSyslog using the command used in Start the temporary AxoSyslog instance in the foreground step.

       syslog-ng -Fe -f /tmp/qdisk/qdisk.conf -R /tmp/qdisk/qdisk.persist -c /tmp/qdisk/qdisk.ctl
   

10. Open another terminal and check the progress by using one of the following methods.

    • Checking the number of stored logs in the disk-buffer (that is, the last number from the output).

          /opt/syslog-ng/sbin/syslog-ng-ctl stats -c /tmp/qdisk/qdisk.ctl | grep 'dst.*queued'
      

    • Checking the status of the disk-buffer file.

          /opt/syslog-ng/bin/dqtool info /tmp/qdisk/syslog-ng-00000.rqf
      

      An empty disk-buffer file will look similar to this:

      Example: empty disk-buffer file status message

      When checking the status of the disk-buffer files, the terminal will display a similar status message for an empty disk-buffer file:

          Reliable disk-buffer state loaded; filename='/tmp/qdisk/syslog-ng-00000.rqf', queue_length='0', size='0'
      

11. Press CTRL+C to stop AxoSyslog.

12. Check the state of the orphan disk-buffer file. For more information, see How to get information about disk-buffer files.

13. If you have more than one orphan disk-buffer file, repeat the steps following the AxoSyslog stop (that is, the steps beginning from overwriting the empty disk-buffer file with the orphan disk-buffer file) for each orphan disk-buffer file.

14. Remove the temporary directory.

    Example: command for removing the temporary directory

    The following command removes the /mp/qdisk temporary directory:

        rm -rf /tmp/qdisk