HP serviceguard t2808-90006 manual Understanding Types of Disaster Tolerant Clusters

Disaster Tolerance and Recovery in a Serviceguard Cluster

Understanding Types of Disaster Tolerant Clusters

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Understanding Types of Disaster Tolerant Clusters

To protect against multiple points of failure, cluster components must be geographically dispersed: nodes can be put in different rooms, on different floors of a building, or even in separate buildings or separate cities. The distance between the nodes is dependent on the types of disaster from which you need protection, and on the technology used to replicate data. Three types of disaster-tolerant clusters are described in this guide:

•Extended Distance Clusters

•Cluster Extension (CLX) Cluster

•Continental Cluster

These types differ from a simple local cluster in many ways. Extended distance clusters and metropolitan clusters often require right-of-way from local governments or utilities to lay network and data replication cables or connect to DWDMs. This can complicate the design and implementation. They also require a different kind of control mechanism for ensuring that data integrity issues do not arise, such as a quorum server. Typically, extended distance and metropolitan clusters use an arbitrator site containing a computer running a “quorum” application. Continental clusters span great distances and operate by replicating data between two completely separate local clusters.

Continental clusters are not supported with HP Serviceguard for Linux. They are described here to show the range of solutions that exist.

Extended Distance Clusters

An extended distance cluster (also known as extended campus cluster) is a normal Serviceguard cluster that has alternate nodes located in different data centers separated by some distance, with a third location supporting the quorum service. Extended distance clusters are connected using a high speed cable that guarantees network access between the nodes as long as all guidelines for disaster tolerant

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