Table of Contents
Tungsten Clustering™ provides a suite of tools to aid the deployment of database clusters using MySQL. A Tungsten Cluster™ consists of three primary tools:
Tungsten Replicator
Tungsten Replicator supports replication between different databases. Tungsten Replicator acts as a direct replacement for the native MySQL replication, in addition to supporting connectivity to Oracle, MongoDB, Vertica and others.
Tungsten Manager
The Tungsten Manager is responsible for monitoring and managing a Tungsten Cluster dataservice. The manager has a number of control and supervisory roles for the operation of the cluster, and acts both as a control and a central information source for the status and health of the dataservice as a whole.
Tungsten Connector (or Tungsten Proxy)
The Tungsten Connector is a service that sits between your application server and your MySQL database. The connector routes connections from your application servers to the datasources within the cluster, automatically distributing and redirecting queries to each datasource according to load balancing and availability requirements.
While there is no specific SLA because every customer’s environment is different, we strive to deliver a very low RTO and a very high RPO. For example, a cluster failover normally takes around 30 seconds depending on load, so the RTO is typically under 1 minute. Additionally, the RPO is 100%, since we keep copies of the database on Replica nodes, so that a failover happens with zero data loss under the vast majority of conditions.
Tungsten Cluster uses key terminology for different components in the system. These are used to distinguish specific elements of the overall system at the different levels of operations.
Table 1.1. Key Terminology
| Continuent Term | Traditional Term | Description |
|---|---|---|
| composite dataservice | Multi-Site Cluster | A configured Tungsten Cluster service consisting of multiple dataservices, typically at different physical locations. |
| dataservice | Cluster | The collection of machines that make up a single Tungsten Dataservice. Individual hosts within the dataservice are called datasources. Each dataservice is identified by a unique name, and multiple dataservices can be managed from one server. |
| dataserver | Database | The database on a host. |
| datasource | Host or Node | One member of a dataservice and the associated Tungsten components. |
| staging host | - | The machine (and directory) from which Tungsten Cluster™ is installed and configured. The machine does not need to be the same as any of the existing hosts in the dataservice. |
| active witness | - | A machine in the dataservice that runs the manager process but is not running a database server. This server will be used to establish quorum in the event that a datasource becomes unavailable. |
| passive witness | - | A witness host is a host that can be contacted using the ping protocol to act as a network check for the other nodes of the cluster. Witness hosts should be on the same network and segment as the other nodes in the dataservice. |
| coordinator | The datasource or active witness in a dataservice that is responsible for making decisions on the state of the dataservice. The coordinator is usually the member that has been running the longest. It will not always be the Primary. When the manager process on the coordinator is stopped, or no longer available, a new coordinator will be chosen from the remaining members. |