Monday, January 28, 2013

Microsoft SQL Server 2012: Overview of AlwaysOn Technologies

MS SQL Server 2012 is released since quite a while now and first customers projects are running. If you are involved in building HA/DR solutions, the new release will be your best friend for the next years.

From my perspective one of the top new concepts in the MS SQL Release 2012 is AlwaysOn. Shortly said, AlwaysOn combines the best things of MS SQL clustering, mirroring and replication to provide better high availability solutions for mission critical systems spawned about different data centers and geographical locations.

Now we have the ability to provide multiple secondary online copies of a database and use them for failover or work offloading scenarios. It allows offloading of resource intensive workloads like backup and maintenance or reporting to other servers than the production. It provides a single connection entry point node for all applications. This concept was used in clustering before and allowed the client to connection to a single virtual node, which provided access to the clustered service.

Another important new feature is Availablility groups which provide much better failover capabilities. An availability group supports a failover environment for a set of databases, known as availability databases, that fail over together. An availability group supports a set of primary databases and one to four sets of corresponding secondary databases. This concept is somehow similar to Oracle resource groups. More information:

The guys from provide some introduction movies which provide a great overview of the new concepts in two parts:

Part 1 : Overview
Part 2: Configuration
Another great introduction viedeo was posted by the uk dpe Team and demonstrates an example configuration:

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