Set up a Failover Server

Failover is the capability to switch over from a primary server to secondary server when the services on the primary server are terminated abnormally. To create a failover setup for Acrolinx, you install the server software files at a shared location and run the server processes on your primary computer. If the Core Platform is unable to run on your primary computer, you can use a second failover computer to access the shared location and run the server processes again.

To create a failover configuration, you must have primary and failover computers to run the server processes, and a shared network location that both computers can read and write to.

If you use Windows and want to start an instance of the Core Platform that is installed on a shared location, you must start the server interactively. You start the server interactively instead of starting the server services to avoid permission problems that can occur when starting services for an application that is installed in a network location.

Also configure a symbolic name for the Core Platform before you begin the setup procedure.

And make sure that the configuration directory is created in the shared network location. In most cases, this is done by default during the first server start. However, if you configure a different location for the configuration directory, you must ensure that this location is on the shared network location.

Configuring the Failover Network Settings

Before you can start the servers on your primary and failover computers, you must update your network settings so that the symbolic name for your server is associated with a specific IP address.

To configure the failover network settings, follow these steps:

  1. Ensure that both computers recognize the symbolic name by adding the symbolic name to the hosts file on the primary and failover computers.
    1. On the primary and failover computers, open the hosts file:

      In Windows: C:\WINDOWS\system32\drivers\etc\hosts

      In a Unix-based operating system: /etc/hosts

    2. Add a line to the hosts file according to the following pattern:

      <LOCAL_IP_ADDRESS>  <SYMBOLIC_NAME>.<LOCAL_DOMAIN>  <SYMBOLIC_NAME>

      For example:

      192.168.2.3  acrolinx-iq.local  acrolinx-iq
  2. Ensure that the IP address of the primary computer is mapped to symbolic name on your DNS server.
    The clients can only connect to the primary or failover server when the symbolic name is mapped correctly.

After you’ve configured the failover network settings, install the Acrolinx in a shared location.

Installing Acrolinx in the Shared Location

When you create a failover configuration, you install the Acrolinx in a shared network location that your primary and failover computers can access. You must also install two separate license files for the primary and failover computers.

To install Acrolinx in the shared location, follow these steps:

  1. From the primary computer, install the Acrolinx software files to the shared location.

    In you're installing on Windows, follow these steps:

    1. Install Acrolinx.
      During the installation procedure, select the shared location as the installation directory and enter the symbolic name for the Acrolinx URL.
    2. Install the guidance package.
      When the installation wizard completes, deselect the option Start Acrolinx Server.

    In you're installing on a Unix-based operating system, follow these steps:

    1. Install Acrolinx.
      During the installation procedure, untar the server package to the shared location and configure the symbolic name as the Acrolinx URL.
    2. Install the guidance package.
  2. Request the license files for both computers.
    1. If your primary computer is running Windows, start the server interactively, open the Dashboard, and note down the hardware ID.
    2. If your primary computer is running a Unix-based operating system start the server, open the Dashboard, and note down the hardware ID.
      Run the server startup script with a user account that has read and write access to the shared directory.
    3. Stop all servers from the Dashboard.
    4. If your failover computer is running Windows, use the following batch script on that computer to start the server interactively:

      <SHARED_INSTALL_DIR>\server\bin\acrolinxRunInteractiveAll.bat

      Use the batch script because there are no Acrolinx shortcuts in the Windows Start menu on the failover computer.

    5. Open the Dashboard, and note down the hardware ID, then stop all servers from the Dashboard.
    6. Request a license for both hardware IDs from the Acrolinx licensing team.
      When requesting the licenses, notify the Acrolinx licensing team that the licenses are for a failover configuration and that both licenses require an identical server ID.
  3. Install the license files on both computers.
    1. When you receive the license files, rename each file so that you can tell which computer each license belongs to.
      For example, you could name the files primary_acrolinx.license and failover_acrolinx.license.
    2. Move the files into the directory <SHARED_INSTALL_DIR>\server\bin and make copy of your primary license file.
    3. Rename the copy of your primary license file back to acrolinx.license so that it becomes the active license file and is recognized by the server.
      Always keep the original failover and primary license files in the bin directory and make a copy of the file that you need.
  4. On the primary computer, start the server interactively and check the log files for errors or warnings.

Switching to the Failover Server

If the service on your primary computer is abnormally terminated due to hardware or operating system problems, you can update the symbolic name on your DNS server to reroute external connections to the failover computer.

To switch to the failover server, follow these steps:

  1. In the directory <SHARED_INSTALL_DIR>\server\bin, delete the file acrolinx.license, make a copy of your failover license file and rename it to acrolinx.license.
  2. Update your DNS server so that the IP address of the failover computer is mapped to symbolic name.
  3. Start the Core Platform interactively on the failover computer. As soon as the clients get the new IP address from the DNS server, they should be able to continue using the Core Platform.

    Ensure that the Core Platform is never running on both computers at the same time. The data in the shared directory might become corrupted.