3.3. Deploying Multisite/Multimaster Clustering

Warning

From v6 of Tungsten Clustering the Multimaster topology has been overhauled. Whilst the Multisite/Multimaster topology is still valid and supported, it is recommended that you use the newer Composite Multimaster topology from v6 onwards.

Please refer to Section 3.4, “Deploying Composite Multimaster Clustering”

A Multisite/Multimaster topology provides all the benefits of a typical dataservice at a single location, but with the benefit of also replicating the information to another site. The underlying configuration within Tungsten Clustering uses the Tungsten Replicator System of Record (SOR) service, which enables multimaster operation between the two sites.

The configuration is in two separate parts:

  • Tungsten Clustering dataservice that operates the main dataservice service within each site.

  • Tungsten Replicator dataservice that provides replication between the two sites; one to replicate from site1 to site2, and one for site2 to site1.

A sample display of how this operates is provided in Figure 3.3, “Topologies: Multisite/Multimaster Clusters”.

Figure 3.3. Topologies: Multisite/Multimaster Clusters

Topologies: Multisite/Multimaster Clusters

The service can be described as follows:

  • Tungsten Clustering Service: east

    Replicates data between east1, east2 and east3 (not shown).

  • Tungsten Clustering Service: west

    Replicates data between west1, west2 and west3 (not shown).

  • Tungsten Replicator Service: east

    Defines the replication of data within east as a replicator service using Tungsten Replicator. This service reads from all the hosts within the Tungsten Clustering service east and writes to west1, west2, and west3. The service name is the same to ensure that we do not duplicate writes from the clustered service already running.

    Data is read from the east Tungsten Clustering and replicated to the west Tungsten Clustering dataservice. The configuration allows for changes in the Tungsten Clustering dataservice (such as a switch or failover) without upsetting the site-to-site replication.

  • Tungsten Replicator Service: west

    Defines the replication of data within west as a replicator service using Tungsten Replicator. This service reads from all the hosts within the Tungsten Clustering service west and writes to east1, east2, and east3. The service name is the same to ensure that we do not duplicate writes from the clustered service already running.

    Data is read from the west Tungsten Clustering and replicated to the east Tungsten Clustering dataservice. The configuration allows for changes in the Tungsten Clustering dataservice (such as a switch or failover) without upsetting the site-to-site replication.

  • Tungsten Replicator Service: east_west

    Replicates data from East to West, using Tungsten Replicator. This is a service alias that defines the reading from the dataservice (as a slave) to other servers within the destination cluster.

  • Tungsten Replicator Service: west_east

    Replicates data from West to East, using Tungsten Replicator. This is a service alias that defines the reading from the dataservice (as a slave) to other servers within the destination cluster.

Requirements.  Recommended releases for Multisite/Multimaster deployments are Tungsten Clustering 5.4.x and Tungsten Replicator 5.4.x