Overview

This section describes GigaSpaces clustering capabilities. It explains the built-in clustering topologies GigaSpaces support and how to use these; clustering concepts and their GigaSpaces implementation; discusses how to configure a cluster and maintain it; and provides a step-by-step guide detailing how to build a common cluster configuration.

For details on how a network of processors elects a unique processor (a leader), and how to avoid split-brain scenarios, refer to the Active Election and Avoiding Split-Brain Scenarios section.

The status of clustered spaces can be viewed using different logging levels. For more details, refer to the Viewing Clustered Space Status section.

Cluster Schema Options

The cluster XML schema configuration file includes tags that define the replication, load-balancing, and failover parameters and policies.

Each cluster has an XML schema configuration file that defines:

• The cluster name, which is unique in the environment. Clients can connect the cluster via its name regardless the actual machines running the cluster spaces.
• Space members and their location – each space member is identified as a 'container:space' pair, for example container1:space1. Spaces can be defined in the configuration file even if they don't exist yet.
• Groups and policies – space members should be grouped; a cluster can include several groups; groups have policies that determine whether clustered spaces perform replication, failover, or load-balancing between them.

Managing Clusters

It can be difficult to understand the structure and settings of a cluster from its configuration file. The GigaSpaces Management Center Space Browser offers a graphic representation of cluster groups, the spaces within them, and the relationships between spaces. The cluster viewer also shows persistency, load balancing and failover settings for any space you click on.

The Cluster view allows you to manipulate cluster members easily.

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Replication Filters

When constructing a replicated space topology you might need to call some business logic when data is replicated. This can be done using the IReplicationFilter plug-in interface. IReplicationFilter methods are called before data is sent to the replication channel from the source space (output mode) and after coming out from the replication channel – i.e. before they are written to the target space (input mode). The replication filter should implement the com.j_spaces.core.cluster.IReplicationFilter interface methods.

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Creating Static Cluster

You can create a cluster from scratch using the Cluster Wizard in the GigaSpaces Management Center. The sections on the right (under Creating Static Cluster) show the overall workflow, and provide step-by-step procedures on how to create the cluster.

An example of a cluster using static cluster configuration can be found in the
<GigaSpaces Root>\examples\Advanced\Data_Grid\multi-site folder.

Section Contents

• Active Election and Avoiding Split-Brain Scenarios — How a network of processors elects a unique processor (a leader), and how to avoid split-brain scenarios.
• Cluster Construction - Cluster Schema — Defining how a dynamic or static cluster should be constructed – configuration, number of members, backups, and so forth.
• Cluster Groups - Cluster Schema — A group is a logical collection of cluster members. Groups are used to define policies for replication, failover, and load-balancing.
• Cluster Members - Cluster Schema — Though you create the members of the cluster one by one, you must decide on the cluster members in advance and add them to the cluster configuration.
• Cluster Name - Cluster Schema — Every cluster has a unique name in the environment, which is specified in the cluster schema.
• Failover Group - Cluster Schema — A failover group defines failover between spaces in the cluster.
• Load-Balancing Group - Cluster Schema — A load-balancing group defines load-balancing between spaces in the cluster.
• Replication Filters — How to call custom business logic when data is replicated in a replicated cluster topology.
• Replication Group - Cluster Schema — A replication group defines replication between spaces in the cluster.
  • Replication Schema — A description of the replication schema options – asynchronous and synchronous replication, multicast and unicast.
• Viewing Clustered Space Status — The status of clustered spaces can be viewed using different logging levels.