A Look at SQL Server Denali AlwaysOn

Microsoft’s SQL Server is nearing the release of Version 11.0, which it has code name Denali (previous code names included Kilamanjaro, Matrix, Katmai, Yukon, and more). Denali figures to be filled with a host of new features, many of which have already been confirmed and discussed at length by Microsoft. One of these new features is SQL Server AlwaysOn – an improvement upon the database mirroring functionality of previous versions of SQL Server.

Among the suite of new features included that AlwaysOn offers to database administrators (DBAs) are: availability groups, active secondaries, failover cluster instances, autostat, and new connection director capabilities.

Particularly intriguing for DBAs is the enhanced data mirroring capability that comes via the availability groups. While older versions of SQL were limited to two servers being mirrored, this new version allows for failover of groups of databases, be it automatic or manual. This reduces the risk for error and allows applications with multiple databases to be failed over correctly.

It’s true that AlwaysOn comes with a more difficult setup for data mirroring which will irk even the most experienced DBAs. While some will be turned off by this and may seek out alternative technologies, don’t let this flaw turn you away from what’s otherwise a greatly improved piece of software. If you were willing to stick with SQL Server back in the 2005 days when data mirroring was in its infancy, then you should be plenty capable of adapting to some of the new setup hurdles in order to reap the benefits that are associated with Denali upon its release.

The enhanced data mirroring that’s associated with Denali may well be its most exciting feature, but there’s a host of other benefits from the other previously mentioned features, including: fast, predictable instance failover, hardware reduction and increased resource efficiency, failover across multiple subnets, and automatic creation/updating of temporary stats for queries running on the readable secondary.

SQL Server Denali will undoubtedly come along with its share of growing pains for DBAs. However, the enhanced functionality it provides – particularly in the data mirroring sphere – means that it should be able to greatly enhance convenience for those who choose to adopt SQL Server development in favor of alternatives that may be behind the curve currently being set by Microsoft. AlwaysOn, along with the rest of Denali’s new features, should keep Microsoft at the front of the data and business intelligence industries.