You can configure multiple Oozie servers against the same database to provide High
Availability (HA) for the Oozie service.
You need the following prerequisites:
- A database that supports multiple concurrent connections. In order to have full
HA, the database should also have HA support, or it becomes a single point of failure.
 | Note |
|---|
The default derby database does not support this.
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- A ZooKeeper ensemble. Apache ZooKeeper is a distributed, open-source coordination
service for distributed applications; the Oozie servers use it for coordinating access
to the database and communicating with each other. In order to have full HA, there
should be at least 3 ZooKeeper servers.
- Multiple Oozie servers.
 | Important |
|---|
While not strictly required, you should configure all ZooKeeper servers to have
identical properties.
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-
A Loadbalancer, Virtual IP, or Round-Robin DNS. This is used to provide a single
entry-point for users and for callbacks from the JobTracker.
The load balancer should be configured for round-robin between the Oozie servers to
distribute the requests. Users (using either the Oozie client, a web browser, or the REST
API) should connect through the load balancer. In order to have full HA, the load balancer
should also have HA support, or it becomes a single point of failure.
