High Availability Wrap Up

High Availability Wrap Up
Today we wrap up the topic of SQL Server high availability. One of the things you may wish to research that we have not covered is the new High Availability technique called “Always On” only available in the Enterprise or greater version of SQL Server 2012.

The Always On capability of SQL Server 2012 is based on clustering. The big difference is that the lesser versions of SQL Server 2012 only support two machines operating in a cluster. If you wish to have more than two servers in your 2012 database cluster you must now purchase an Enterprise license or better.

One capability in Always On is its support for multiple active readable secondary servers and multi-site failover clustering. If you are already using Enterprise licensing for your SQL Servers, Always On may be a good solution for your co-location failover needs.

Here are some more comments from our readers:

Bruce:
Thanks for your article. My understanding on licensing for Mirroring is that the mirror only has to be licensed if it has other databases on it. As long as it is just used as only a mirror it doesn’t need a license. This came up during a conference call with our Microsoft sales rep.

We have found that having an aggressive backup schedule works better for us. We do a daily full backup and transaction log backups every 15 minutes. It doesn’t provide for automatic failover, but automatic failover doesn’t work if the two databases are out-of-sync.

Leif:
We moved to mirroring in 2007 and never looked back. We rarely have a problem with the service and it affords us great flexibility and security. One thing I want to clarify is that, while the hardware costs double, the SQL Server licenses do not so long as the mirrors are passive (not serving production data or other workload). This is documented in the MS SQL Server 2012 Licensing Guide under the Failover Basics section.

We also use (transactional) Replication transfer most production data to our reporting servers to serve internal clients requests as well as application servers. Regarding costs, while the servers are high-end the workload is generally less and read-only so we can support databases from all (3) production servers on each reporting server (we have two for redundancy). Also, there is some extra deployment work when DDL is implemented.

Leif also provided some additional resources in the form of documents. The first was SQL Server 2012 Licensing Reference Guide as a PDF. The second was SQL Server 2008 Pricing and Licensing as a Word document. I’m including some links from those documents with additional information. You can do a Google search to locate those documents yourself if they are of interest. I don’t have a method to include them here.

Pricing for Microsoft SQL Server 2012

See http://www.microsoft.com/sqlserver/en/us/get-sql-server/how-to-buy.aspx for great overview of SQL Server 2012. It also has links to more documentation for licensing information, as well as tools for producing a quote.

For information on the compute capacity limits for each edition of SQL Server 2012, visit:
http://msdn.microsoft.com/en-us/library/ms143760.aspx.

Thank you all who have shared your experience. I have found it quite valuable personally, and am sure it will assist others.

See you next week with new topics. Feel free to send in ideas for topics you find relevant by writing btaylor@sswug.org.

Cheers,

Ben

$$SWYNK$$

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