Sun Microsystems Portal Server 6 2005Q1, Planning Manual

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Working with Portal Server Building Modules
Chapter 5 Creating Your Portal Design 95
Redundancy is equally important to the directory master so that profile changes
through the administration console or the Portal Desktop, along with consumer
replication across building modules, can always be maintained. Portal Server and
Access Manager support MMR. The NSPOF scenario uses a multi-master
configuration. In this configuration, two suppliers can accept updates, synchronize
with each other, and update all consumers. The consumers can refer update
requests to both masters.
SRA follows the same replication and load balancing pattern as Portal Server to
achieve NSPOF. As such, two SRA Gateways and pair of proxies are necessary in
this scenario. The SRA Gateway detects a Portal Server instance failure when the
instance does not respond to a request after a certain time-out value. When this
occurs, the HTTPS request is routed to a backup server. The SRA Gateway
performs a periodic check for availability until the first Portal Server instance is up
again.
The NSPOF high availability scenario is suitable to business critical deployments.
However, some high availability limitations in this scenario might not fulfill the
requirements of a mission critical deployment.