Sun Cluster Geographic Edition software is a layered extension of the Sun Cluster software. The Sun Cluster Geographic Edition software protects applications from unexpected disruptions by using multiple clusters that are separated by long distances and by using a redundant infrastructure that replicates data between these clusters. Data replication software enables applications that are running on a Sun Cluster Geographic Edition cluster to tolerate disasters by migrating services to a geographically separated secondary cluster. A disaster such as an earthquake, a fire, or a storm might disable the cluster at the primary site. If a disaster occurs, the Sun Cluster Geographic Edition cluster can continue to provide services by using the following levels of redundancy:
A secondary cluster
Duplicated application configuration on the secondary cluster
Replicated data on the secondary cluster
This chapter gives a high-level overview of the Sun Cluster Geographic Edition product. It contains the following sections:
Business continuity is a wide-ranging subject that analyzes all aspects of how a business maintains service to its customers when faced with an unexpected disaster. When creating a business continuity plan, companies must trade off the cost of the additional required infrastructure such as hardware, software, telecommunications, and buildings, against the risks, such as the costs of a prolonged outage. As a result, systems that are critical to the business and those for which there is a legal requirement are the top priorities.
For a service to be available, all the constituent pieces must also be available. The key issue is rapid recovery of individual service elements. Outages can occur from hardware failure such as component or power failures, or from software failures such as operating system panics and application crashes. Network connectivity failures can also affect service availability. Most of these failures can be masked through component redundancy or by having a standby server ready to take over the workload. The Sun Cluster Geographic Edition software is a building block for disaster tolerance which provides a framework that enables data services to be moved between a primary cluster and a geographically separated secondary cluster in a controlled fashion.
The Sun Cluster Geographic Edition software provides a suite of tools to manage and configure geographically separated clusters with a migration of services between sites. The Sun Cluster Geographic Edition software can manage availability across multiple physical locations through robust security, application service migration, and data replication to tolerate disaster across an enterprise system.
The Sun Cluster Geographic Edition product enables an improved combination of performance, cost, and separation of data recovery points. This combination contrasts with campus or metro clustering, which consists of a single cluster with widely separated nodes. The Sun Cluster Geographic Edition product provides the management and configuration tools for geographically separated clusters.
A configuration that is running the Sun Cluster Geographic Edition software consists of a set of clusters that are geographically distributed. The primary cluster provides application services. The secondary cluster in the set is an alternative site that can take over the primary cluster services if a disaster occurs. The Sun Cluster Geographic Edition software manages configuration, data replication, and heartbeat monitoring between the two clusters and enables data to be decentralized across multiple disaster recovery sites.
Disaster tolerance is the ability of a system to restore an application on a secondary cluster when the primary cluster fails. Disaster tolerance is based on data replication and failover. The Sun Cluster Geographic Edition software enables disaster tolerance by redundantly deploying the following:
Highly available clusters that are geographically separated
Data replication at either the host or the storage level
Backups and restoration and data vaulting
Data replication is the process of continuously copying data from the primary cluster to the secondary cluster. Through data replication, the secondary cluster has a recent copy of the data on the primary cluster. The secondary cluster can be geographically separated from the primary cluster.
Failover is the automatic relocation of a resource group or device group from a primary cluster to a secondary cluster. If the primary cluster fails, the application and the data are immediately available on the secondary cluster.
The Sun Cluster Geographic Edition software supports two types of migration of services: a switchover and a takeover. A switchover is a planned migration of services from the primary cluster to the secondary cluster. During a switchover, the primary cluster is connected to the secondary cluster and coordinates the migration of services with the secondary cluster. This coordination enables the data replication to complete and ensures that services can be transferred from the primary cluster to the secondary cluster without loss or corruption of data.
A takeover is an emergency migration of services from the primary cluster to the secondary cluster. A system administrator can initiate a takeover to recover from a disaster. Unlike a switchover, the primary cluster is not connected to the secondary cluster during a takeover. Therefore, the primary cluster cannot coordinate with the secondary cluster to migrate the services. Because of this lack of coordination, the risk of data loss and data corruption in a takeover is higher than it is with a switchover. The Sun Cluster Geographic Edition software uses dedicated recovery procedures during a takeover to minimize data loss and data corruption.
The Sun Cluster Geographic Edition product provides the following features:
Failure detection of multiple clusters that are geographically separated
Configurable heartbeat monitoring between clusters
Application resource switchover from one cluster to another cluster
Remote management of partner clusters through a graphical user interface (GUI) and a command-line interface (CLI)
Data replication between geographically separated clusters
Secure administration interfaces through role-based access control (RBAC)
Secure Sockets Layer (SSL) authentication and encryption for communication between nodes or clusters
Configurable IPsec security for data replication between clusters and for heartbeat communication between clusters
Ability to automatically run a script when a heartbeat-loss notification is issued
The Sun Cluster Geographic Edition software provides tools for managing data replication between geographically separated clusters. The software supports the following data replication products:
Sun StorEdgeTM Availability Suite
Sun StorageTekTMAvailability Suite
Hitachi Universal Replicator
EMC Symmetrix Remote Data Facility
The Sun Cluster Geographic Edition software supports Oracle Real Application Clusters with Hitachi TrueCopy and Universal Replicator software.
The Sun Cluster Geographic Edition product provides highly available services within a cluster by utilizing Sun Cluster resource management features.
You can configure, control, and monitor partnerships, heartbeats, and protection groups either through the Sun Cluster Manager Geographic Edition GUI or through the command-line interface (CLI).
The Sun Cluster Geographic Edition CLI contains a set of dedicated commands.
The Sun Cluster Manager Geographic Edition GUI is an extension of the Sun Cluster GUI. The GUI provides a visual display for most of the operations that are available through the CLI. You can manage and monitor geographically separated clusters by using the Sun Cluster Manager Geographic Edition GUI.