Handling failover
In a cluster of MDM Servers, each instance of MDM Server - that is to say, each node - is independent. As such, whenever a session is initiated on a particular node, it remains on that node. In other words, for that session, any HTTP requests coming from the same user are always sent to the same node.
The following table describes what happens when an individual node fails.
| Source | On failover | Limitations |
|---|---|---|
|
Talend MDM Web UI |
Users currently connected on live nodes see no difference. New users can connect normally. |
Users currently connected on the failed node are disconnected from their session and redirected to the login page, as happens when a session expires. |
|
Running Jobs |
Jobs connected on live nodes finish normally. |
Jobs connected on the failed node will also fail, if they use the tMDMConnection component. However, Talend Administration Center can rerun the Jobs immediately and route them to another node. For Jobs which do not use the tMDMConnection component, only one record is rejected. |
|
Triggers |
The Event Manager queues ensure that all asynchronous Triggers eventually run. |
Synchronous Triggers running on the failed node also fail. |
|
beforeSaving/beforeDeleting Processes |
All Processes on live nodes run normally. |
Processes on the failed node also fail, causing the create, update, or delete action to be rejected. |