After hearing all of the great sessions at SQL PASS Summit on Availability Groups are you thinking about biting the bullet and writing the check to upgrade to SQL Server 2012 Enterprise Edition to take advantage of this great feature? Before you get your checkbook out, stop and ask yourself these questions.
Do I use/need
- to lower my SQL Server cost?
- replication or log shipping?
- to minimize the impact that replication has on the performance of my application?
- Lync Server, Dynamics CRM or other applications that use distributed transactions?
- to ensure that SQL Agent jobs such as database backups, optimizations, DTS and others continue to run regardless of the node in service?
- to ensure that SQL login accounts are kept in sync between cluster nodes?
- to minimize my administrative burden?
If you answered yes to any of these questions, you may want to reconsider your options when it comes to your SQL Server HA/DR deployment. While AlwaysOn Availability Groups certainly have their place, you may want to consider the overhead associate with them as I discussed in my previous article. Also, you really need to consider what applications will be utilizing the SQL Server database as not all applications support AlwaysOn Availability Groups, including many of Microsoft’s applications such as Lync Server and others (check your application documentation).
What I would propose instead is to consider building a traditional active/passive cluster which overcomes all of the limitations listed above, but instead of using shared storage use the cluster integrated block level replication solution from SIOS Technology called SteelEye DataKeeper Cluster Edition. Using this replication solution you are able to eliminate the SAN as a single point of failure as well as eliminate all of the limitations associated with AlwaysOn Availability Groups listed above. When you consider the possibility of using high speed local storage solutions such as @Fusionio in conjunction with DataKeeper you can have a high speed, highly available SQL Server cluster with a minimal investment in hardware and software. And best of all, this solution works with SQL 2005/2008/2008R2/2012 Standard Edition as well as Enterprise Edition, so the cost saving alone on SQL Server licensing can more than pay for the solution (more on costs saving in my next post).
You can by a 2 server pre-package solution that includes HP, Dell or Supermicro servers, Fusion-io ioDrives and DataKeeper software to help you deploy you first high speed, highly available SQL cluster. For more information see the press release here.