EXPERT RESPONSE
Failover clustering is when two or more servers with specialized hardware and software share resources and appear to client applications as a single server (called a virtual server) with a different name and IP address than the individual servers which form the cluster. If something happens to one of the servers, the cluster will failover to another node and the client will experience minimum downtime during the failover and can reconnect to the virtual server.
Clustering protects from localized hardware failure (for example a power supply failure on one node), but does not protect from a power failure in the building supplying all nodes in the cluster. Geo-clustering can keep data in sync between two geographically dispersed servers, and should you experience a regional failure (a flood) your applications can reconnect to the DR site.
The challenge for VARs is to:
- Provide servers with hardware redundancy so that they will be as resilient to hardware failures localized to that node
- Provide clusters which will provide high availability so the cluster will be as resilient as possible to node failures (for example a unexpected SQL Server shutdown due to a program fault, or a planned outage for hardware servicing or a service pack). In a cluster you can take a node offline by failing over to other nodes in the cluster.
- Provide DR solutions which will protect the client's data against regional failure by keeping a DR site in sync with a near real time copy of your data.
|
