Configuring Eclipse Amlen servers as an HA pair by using the Amlen WebUI

In this scenario, a server that has HA disabled is now paired with another server to act as its backup. System administrators can configure a pair of servers for high availability (HA) by using the High Availability page in the Amlen WebUI.

You can configure Eclipse Amlen servers for high availability by using the Amlen WebUI or by using REST Administration APIs. For more information about using the REST Administration APIs to configure servers for high availability, see Configuring Eclipse Amlen servers as an HA pair by using REST Administration APIs.

In this scenario, Server A is already member of a cluster, and becomes the primary node. Server B becomes the standby node in the HA pair. Server A can be a server that has data on it. Server B must be a newly installed Eclipse Amlen server or you must complete Step 1 to remove any pre-existing data.

Important: The following scenario describes changing one server from standby to primary if one of the servers is stopped.

An HA pair of servers are identified as HA1 and HA2. Both are configured with Auto-detect selected under Startup Mode.
- HA1 is active and is the standby server
- HA2 is active and is the primary server
HA2 is stopped. So, now HA1 is active and is the standby server.
Next, you stop HA1. Now both HA1 and HA2 are stopped.
If you restart HA1, you will get a message saying it can't determine the true HA status because HA2 is still down.
In order to bring HA1 up as the primary with HA2 still stopped, you need to select Standalone under Startup Mode.

Do not select Standalone under Startup Mode if another node is already running and is acting as a primary. Doing so could create a split-brain condition, where both instances act as primary nodes. In this instance, both nodes will go into maintenance mode.

Optional: If Server B is a newly installed server, you do not need to perform this step. If Server B is not a newly installed server and has been used for messaging services, you must delete any JMS queues that exist on the server and then clean the store.
1. If necessary, delete any existing JMS queues. For more information about deleting queues, see Configuring queues by using the Amlen WebUI.
2. Click Server Control in the Server menu.
3. Click Clean store.
  This step cleans the store and restarts the server.
Eclipse Amlen supports user provided TLS credentials for High Availability Pairing. Providing the credentials prior to creating the HA pair is recommended to avoid migrating the cluster. See High Availability Pairing: User Provided TLS Credentials.
Configure high availability on Server A:
1. From the Server menu, select High Availability.
2. Click Edit in the Configuration panel.
3. Select High Availability Enabled.
4. Complete the High Availability Group field.
  The value must be the same on Server A and Server B.
5. Under Replication and Discovery Addresses:
  1. Type the IP address of the replication interface of the local node in Local Replication Address. For example, 192.0.2.0
  2. Type the IP address of the discovery interface of the local node in Local Discovery Address. For example, 192.0.3.0
  3. Type the IP address of the discovery interface on the other node (Server B) in the HA pair in Remote Discovery Address. For example, 192.0.3.2
6. Expand the Advanced Settings section by clicking the twistie.
  1. Ensure that Auto-detect is selected as the Startup Mode.
  2. Select the When both nodes start in auto-detect mode, this node is the preferred primary node check box.
  3. In the Discovery Timeout field, type the amount of time in seconds that within which an server that is started in auto-detect mode has to connect to the other server in the HA pair.
  4. In the Heartbeat Timeout field, type the amount of time within which an server has to determine if the other server in the HA pair has failed.
7. Click Save.
8. Click Restart Later.
Configure high availability on Server B:
1. From the Server menu, select High Availability.
2. Click Edit in the Configuration panel.
3. Select High Availability Enabled.
4. Complete the High Availability Group field.
  This value must match the value on Server A.
5. Under Replication and Discovery Addresses:
  1. Type the IP address of the replication interface of the local node in Local Replication Address. For example, 192.0.2.2
  2. Type the IP address of the discovery interface of the local node in Local Discovery Address. For example, 192.0.3.2
  3. Type the IP address of the discovery interface on the other node (Server A) in the high availability pair in Remote Discovery Address. For example, 192.0.3.0
6. Expand the Advanced Settings section by clicking the twistie.
  1. Ensure that Auto-detect is selected as the Startup Mode.
  2. Ensure that the When both nodes start in auto-detect mode, this node is the preferred primary node check box is not selected.
  3. In the Discovery Timeout field, type the amount of time in seconds that within which an server that is started in auto-detect mode has to connect to the other server in the HA pair.
  4. In the Heartbeat Timeout field, type the amount of time within which an server has to determine if the other server in the HA pair has failed.
7. Click Save.
8. Click Restart Later.
Restart both Eclipse Amlen servers:

Tip: As a best practice, restart the standby server first. Then restart the primary to limit the amount of time that the primary spends waiting for the standby to become available.
1. Click Server Control in the Server menu.
2. Restart the server by clicking Restart the server.

When the HA pair is up and running, you can view the status of each server from the Status menu on the Amlen WebUI. You can view further information on the status of the server by using the Server Control page. You can view further information about the HA role of the server by using the High Availability page.