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SQL Server 2012 – Always On
SQL Server has always focused on high availability solutions. In SQL Server 2008 R2 – the common options included clustering, mirroring, log shipping and replication. These solutions offer different options for different scenarios. If you want “service level” high availability – clustering is the right choice. Mirroring offered 1 to 1 database copy with automatic failover. Log shipping offered primary to multiple secondary database copies, without automatic failover. Replication allows us to select “parts of a database” to replicate to other servers. All of these ideas warrant much more detailed conversation – unrelated to the title of this blog.
SQL Server 2012 (Currently SQL Denali CTP3) introduces a new feature – Always On Availability Groups. Initial observations (from reading TechNet and working through hands-on labs) – Microsoft has taken the strong points from clustering and the strong points from Mirroring and combined them into one solution. Most notable consideration is the requirement for Windows Clustering.
Administrators build these Availability Groups which are comprised of Application Databases which work and fail(over) together – refered to as Availability Databases (give them a zero on creative naming ideas). The read/write availability group is called the primary replica and up to 4 secondary replicas which can be read only.
Additionally – there are options you can configure related to the transaction commit – asynchronous & synchronous (obvious) and several forms of failover.
From the looks of it – this will be widely accepted in the community. As always the case with CTP, Beta and everything else – the information stated above is subject to (and probably will) change prior to RTM versions of the product.
CertificationCamps.com is modifying our Microsoft training content to bring these new features into our SQL Administrator Bootcamp. We have added labs which explain the new SQL Server 2012 Availability Groups into our existing Cluster Hands On Instructor Led Demonstration.
Chester Flake
CertificationCamps.com