AlwaysOn was introduced in SQL Server 2012, and there are some enhancements in SQL Server 2014:
- Now support up to 8 secondary replicas that remain available for reads at all times, even in the presence of network failures. Failover Cluster Instances now support Windows Cluster Shared Volumes, improving the utilization of shared storage and increasing failover resiliency. Finally, various supportability enhancements make AlwaysOn easier to use
- More secondaries for AlwaysOn Availability Groups: Increased from 4 secondaries to 8
- Improved reliability for AlwaysOn Availability Group secondaries: The secondaries will now stay online if the primary goes offline
- Can use Azure VMs as AlwaysOn Availability Group replicas: When adding a replica you can specify an Azure VM
More info:
AlwaysOn in SQL Server 2014 CTP1
(Almost) Everything You Need to Know About the Next Version of SQL Server
Changes to SQL Server 2014 Always On Availability Groups
