## JReport Enterprise Server cluster

A JReport Enterprise Server cluster is a group of servers that work together to provide cluster-wide shared resources, security, schedule and version services. There is one admin server, one or more backup servers, and zero or more slave servers in a JReport Enterprise Server cluster.

The JReport Enterprise Server cluster provides the following major benefits:

- Manageability: All users and resources can be controlled from a central place, remotely.
- High-Availability: When one server fails to perform, the tasks running on it will be re-allocated to other servers. If a server has already been fully utilized, the tasks sent to it will be allocated to the other servers.
- Scaleable: You can add or remove servers dynamically according to your needs.

There are three roles in a JReport Enterprise Server cluster. They are one admin server, one or more backup servers, and any number of slave servers. Each server has its own responsibilities. You set a server to perform a specific role in a JReport Enterprise Server cluster by configuring its properties.

### Admin server

There must be one and only one admin server in a JReport Enterprise Server cluster. In a JReport Enterprise Server cluster, the admin server maintains the shared resources and performs security administrative tasks. The admin server automatically detects the overloaded member servers and re-partitions tasks among all servers in the JReport Enterprise Server cluster. You can monitor and administer all the servers in the cluster using the admin server.

### Backup server

There should be at least one backup server in a JReport Enterprise Server cluster. If the admin server is shut down or breaks down, the backup server with the highest priority in the cluster will promote itself to be the admin server and take over all the administrative tasks.

### Slave server

There can be zero or more slave servers in a JReport Enterprise Server cluster. On a slave server, you can perform tasks such as run report sets and submit scheduled tasks. Slave servers can receive tasks directly from users or from the admin server. When the number of concurrent report sets running on a server is equal to the number of concurrent report sets that is permitted by its license, the server will inform the admin server. If a further task is submitted to this server, it will be sent to the admin server and the admin server will then re-allocate it to other servers.

###### Related topics:

- Clustering
- Managing JReport Enterprise Server clusters