High Availability

Windows Server AppFabric Caching
When enabled, high availability of WSAF Caching maintains a "primary" copy of each object as well as a "secondary" copy of each object on a remote cache host for fault tolerance. This feature is disabled by default, and it is limited to use on Enterprise Editions of Windows Server. (Because there is no Enterprise SKU for Windows Server 2012, WSAF high availability was recently made available to Standard Editions of Windows Server 2012.)
ScaleOut StateServer

ScaleOut hosts always store objects in a highly available manner—the primary copy of an object is called a "master" and the secondary backups are referred to as "replicas". Management and configuration of replicas is automatic and transparent.

Replicas are kept fully consistent with master objects, and the service can be configured to store 1 or 2 replicas of each object for fault tolerance; using two replicas allows your data grid to handle the sudden loss of two ScaleOut hosts without data loss.

More information about fault tolerance and recovery from failures is available in the Recovery from Failures topic in the ScaleOut StateServer Help online guide.