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12
Clustering Reports Servers
A cluster is a virtual grouping of servers into a community for the purpose of sharing
request processing efficiently across members of the cluster. Clustering in OracleAS
Reports Services is peer-level, which means that all members of the cluster take equal
responsibility for sharing and processing incoming requests. If one member is shut
down, the other members carry on managing the request load. If the output is present
in one member’s cache, another member can use it. There is no single-point-of-failure,
where one machine's malfunction brings the whole system down.
This chapter contains information about enrolling a server in a cluster and benefits of
clustering servers together. It contains the following sections:
■ Cluster Overview
■ Setting Up a Cluster
12.1 Cluster Overview
Assume you have the following servers:
serverA.cluster1
serverB
serverC.cluster1
ServerA.cluster1 and serverC.cluster1 are members of the same cluster
called cluster1. They cooperate to process requests from a client. If a client sends a
synchronous request to serverA.cluster1 and it does not have an idle engine of
the specific job type, then it checks to see if serverC.cluster1 does. If
serverC.cluster1 does have an idle engine, then serverA.cluster1 passes the
request to serverC.cluster1 for processing.
In this example, ServerB is a stand-alone server and cannot receive processing
requests from other servers, nor can it send processing requests to other servers.
You can have an unlimited number of servers in a cluster. If a cluster member is shut
down, then it redistributes its pending synchronous jobs to another server in the
cluster. As long as one server in the cluster is running, the cluster is working.
When the cluster is making its decision as to where an upcoming scheduled or
immediate request should be processed, it prioritizes according to the following
criteria:
1. Does any server in the cluster have information in cache that matches the request?
2. Is there a current, similar job in the queue?
3. Is an idle engine of the particular job type available?
Clustering Reports Servers 12-1