Configuring a backup license server (Windows)

A backup license server will take over the task of serving Synergy licenses in the event that the primary server becomes unavailable. If your primary server is using REV11 licensing, the backup server must also use REV11 so that licensing features (such as fuzzy matching) that were available to license clients under the primary server continue to be available when the backup server activates. (The backup license server does not poll the Synergy License Web Service.) The license clients may be running older versions of Synergy/DE.

If the primary server goes down, the license clients will automatically switch to using the backup license server. The backup server will run for up to 21 days (regardless of when your subscription license expires). You must restore the primary server (or designate a new primary server) before 21 days have elapsed in order to continue serving licenses. Once the primary server is restored, the serving of licenses automatically switches back to that machine.


The primary server checks continuously to ensure that the backup server is present. If the primary cannot detect the backup for a period of 7 days (168 hours), it disconnects itself from the backup, propagates the change to all the clients, and logs this message to the Windows event log: “Synergy License Manager backup server name was removed because primary could not connect to backup before timeout was exceeded.”

This topic includes the following sections:

Requirements and recommendations

To implement a backup license server you must first purchase a Backup License Server (BLS) license. Contact your Synergex account executive for information.

On the backup server machine, Synergy/DE must be installed to run locally, and the backup server must be a license client to the primary server. All clients, including the backup license server, must address the primary server by name, not by IP address.

We recommend the following:


Each time you configure a license client to be a backup license server, the BLS license configuration counter is reduced. You’ll see a warning message on the eighth configuration, which is the maximum. When you see this message, contact Synergex Customer Service to obtain a replacement product key for your BLS license. To check how many configurations you have remaining, run lmu (without any options). See Displaying backup license server information.

Setting up the license servers

On the primary license server

1. Install Synergy/DE. When the installation program prompts you for the license configuration, select Network Server.
2. License your Synergy products. (With REV11 licensing, this happens automatically.) You must have a backup license server (BLS) key on the primary server; this enables another machine to become a backup server to this primary server.
3. If you plan to run the primary license server on a non-default port, change it now, before setting up the backup license server. See Changing a license server’s port.

On the backup license server

1. Install Synergy/DE to run locally. You must install at least Core Components. If the primary server uses REV11 licensing, either Synergy/DE 11 or the REV11 licensing upgrade package must be installed on the backup server.
2. When the installation program prompts you for the license configuration, select Network Client and specify the primary server by DNS name—not IP address—in the Server Name field.

If the primary server is not running on the default port (2380), specify its port by appending a colon followed by the port number to the end of the server name (e.g., Tiger:5555).


If the backup server machine had a previous version of Synergy/DE installed, you will not be prompted for the license configuration during installation. Take a moment to open SynConfig and check the Licensing tab (or run lmu without any options) to verify that the backup server machine is a license client to the primary server. If it is not, stop! Change the license configuration of the backup server now, before continuing with this procedure. See Modifying license configurations (Windows).

3. After the installation is complete, start the Synergy Configuration Program and click the Advanced button on the Licensing tab.
4. In the Advanced License Manager dialog box, select the “Be a backup server” option.
5. Click OK. You’ll see the backup server status displayed on the Licensing tab.

Once the backup license server is configured, you will be able to see its status on the Licensing tab of the primary server or any of the license clients. See Checking the status of the license servers.


By default, the backup license server will use the default port 2380 when it becomes the active license server. (This is the case even if the primary server was running on a non-default port.) Once the backup license server is configured, you can specify a different port using the lmu -xb command followed by the lmu -nb -po#### command. Note that you do not have to do anything on the license clients to accommodate this change; they will automatically be notified.

On the license clients

When you install Synergy/DE on the license clients, specify the primary server by DNS name—not IP address—in the Server Name field. If the license clients are Synergy/DE Client machines, specify the name of the primary server in the setup.ini file.


The name of the backup license server is sent to the license client when the client makes a license request to the primary server. This value is then stored in the registry on the client. This means the client must have made a successful connection to the primary server in order to be able to use the backup server.

If the backup license server name changes, you should log onto each client machine as a user with elevated privileges and run a Synergy application or lmu. This will ensure that the new backup license server name is properly registered on the license client for all users.

Checking the status of the license servers

Once you have the primary and backup license servers configured, you can check their status from any client by looking at the Licensing tab in the Synergy Configuration Program. Next to the name of the primary and backup servers, you’ll see a status of active, ready, or inaccessible.

Changing the backup license server for a primary server

To change which machine is the backup license server to a particular primary license server,

1. Configure a new machine to be a backup license server following the instructions in On the backup license server.
2. If the new machine has a different name, log onto each license client and run a Synergy application or lmu so that the client is informed of the name change. (See the important note above.)

Once a new backup server is configured, the old backup server will automatically cease to be a backup server. If the machine is running, this could take up to 10 minutes because that is how often the backup server checks for changes to the licenses. If desired, you can stop and restart the old backup server to expedite the process. If the old backup license server is off, it will update the next time it boots up.

Changing the primary server for a backup license server

Follow these instructions if you want to change the primary server machine and retain the existing backup license server as a backup to the new primary. These instructions also apply if the primary server has gone down and you need to designate a new machine to replace it while the backup license server is running.

1. Install and license Synergy/DE on the new primary server. You must have a Backup License Server (BLS) product key. If the new primary server has the same name as the old primary server, this is all you need to do.
2. If the new primary server has a different name than the old server, do the following on the backup server:

Removing a backup license server

Follow these instructions to completely remove a backup license configuration. This procedure is done on the backup server. If you do not have access to that machine, see the note below for the command line procedure.

1. On the backup server, start the Synergy Configuration Program and click the Advanced button on the Licensing tab.
2. Clear the “Be a backup server” check box and click OK in the Advanced License Manager dialog.
3. Click OK on the Licensing tab. The backup license server will revert to client status and the change will be propagated to the primary server and all the license clients.

To remove a backup license server from the command line, run lmu with the -xb option. Normally, you would do this from the backup server machine; however, if that machine is not available or no longer exists, you can run lmu -xb from the primary server. It will remove backup licensing from the server and propagate the change to all license clients, including the backup license server.