Home > Workload Solutions > SQL Server > White Papers > Dell PowerMax 2500 and 8500 Best Practices for Mission Critical SQL Server Databases > WSFC and High Availability
On the Windows operating system, SQL Server gains high availability by integrating with WSFC and Always On Failover Cluster Instances (FCI).
WSFC is a group of independent Windows servers (cluster nodes) that work together to increase the availability of cluster roles, which are typically applications (such as SQL Server) and services (such as networking and storage). If a node fails, WSFC automatically makes the cluster roles available on a healthy node in the cluster.
WSFC also provides Cluster Shared Volume (CSV) functionality, which allows access to shared storage from any node in the cluster. It improves the speed in which cluster roles are moved between nodes as the storage is already available.
FCI uses WSFC so that a SQL Server instance can be intentionally moved or automatically failed over between nodes in WSFC. As a result, a failure of resources required for the SQL Server cluster role on one node in the cluster causes the cluster role to failover to a healthy node in which the SQL Server instance and databases can automatically resume operations.
While WSFC and FCI provide high availability for SQL Server instances in the data center across a cluster of servers, PowerMax replication options provide additional capabilities. These capabilities include stretching a WSFC across buildings or data centers using SRDF/Metro, creating synchronous and asynchronous remote replication for SQL Server using SRDF/S and SRDF/A respectively, and creating local or remote snapshot and clone copies of the databases using TimeFinder/SnapVX and TimeFinder/Clone.
An example of using PowerMax local replication with SQL Server on Windows is shown in Example: using snapshots to create a SQL Server database copy.