Microsoft has a methodology for developing and distributing updates to SQL Server, which they call the Incremental Servicing Model (ISM).  This model has a hierarchy of on-demand hotfixes (HFs), Cumulative Updates (CUs), and Service Packs (SPs) that are used to distribute updates to SQL Server. 

Microsoft’s official policy and guidance about when and whether to apply SQL Server updates changed on March 24, 2016, as described here. It is important that DBAs understand how this update system works whether they are working with traditional on-premises SQL Server or SQL Server running in an Azure VM (or any other IaaS cloud solution such as Amazon EC2).

Why do you need to maintain SQL Server?

Actively maintaining your SQL Server instances by proactively installing CUs and SPs as they become available will make your database server more reliable and possibly perform better. Microsoft has historical CSS data that indicates that a significant percentage of customer issues have already been fixed in a previously released CU, that had not been applied by the customer. My own personal experience as a DBA and consultant reinforces this view.

What happens if I don’t maintain my SQL Server instances?

You are more likely to run into problems that Microsoft has already fixed (because other customers have run into them). If your build of SQL Server is old enough, it may actually become what is called an “unsupported service pack”, which means that Microsoft CSS may be unwilling to fully support you (beyond basic troubleshooting) until you update to a supported service pack level. You don’t want to find yourself in this situation!

Are there any other benefits from updating SQL Server?

Developing a detailed plan for how you test and deploy a SQL Server update, and then actually implementing and updating the plan on a regular basis forces you and your organization to have a plan you also can follow whenever you make any kind of change or update to your database servers or the applications that use them. If you have any sort of HA/DR technology in place, updating SQL Server gives you an opportunity to use it in a planned fashion to minimize your downtime. Doing this on a regular basis validates your HA/DR solution and increases your confidence that it actually works as designed.

Are there any risks from updating SQL Server?

Certainly. Anytime you make any change to a computer system, there is a chance that something can go wrong. That is why you should have a written plan for how you test and deploy a SQL Server update that also includes how to rollback and recover in case something does go wrong. In reality, it is actually quite rare for a SQL Server update to cause a problem, but that doesn’t mean you should not be ready to deal with it if it does happen. Having a detailed plan that you actually follow dramatically decreases the chances of having any issues when you deploy your SQL Server update to Production.

How often does Microsoft release Cumulative Updates?

Microsoft releases Cumulative Updates every eight weeks for the versions of SQL Server that are still in mainstream support. This includes SQL Server 2012, SQL Server 2014, and SQL Server 2016. Currently, the CU release cycles for SQL Server 2012 and SQL Server 2016 are in sync, while SQL Server 2014 releases CUs slightly later. Hopefully, they will get the CU release cycle for all three versions back in sync.

How do I find out about new SQL Server Cumulative Updates?

The first place to look is the SQL Server Release Services blog. You can also check these Microsoft KB articles:

How do I find more information about this subject?

You can watch my Pluralsight courses SQL Server 2012: Installation and Configuration and SQL Server: Installing and Configuring SQL Server 2016, and read my article on SQLPerformance.com, Making the Case for Regular SQL Server Servicing.

You can attend one of our in-person training classes, such as IE0: Immersion Event for the Accidental/Junior DBA or IEHADR: Immersion Event on High Availability and Disaster Recovery. You can also contact me if you have specific questions. And, if you want to find all of our SQLskills SQL101 blog posts – check out: SQLskills.com/help/SQL101

Thanks for reading!