What is the Difference in SQL Server FCIs and AGs? A Short Summary
“What’s the difference in SQL Server FCIs and AGs?” That question comes up frequently when talking High Availability and Disaster Recovery (HADR). It’s especially important when “Everything stops and people can’t do their jobs if SQL Server is unavailable.”
There are a lot of how-to articles on the internet for setting up Always On Failover Clustered Instances (FCIs) and Always On Availability Groups (AGs). So, I won’t deep dive into the technologies. Rather I’ll share some of their key, high-level differences. The goal is to help you identify the better choice for your environment. Even with that narrow scope, this is a big topic.
How do FCIs and AGs compare?
The following chart summarizes the differences.
* See the SQL Server 2019 Licensing Guide and consult a licensing expert if you have any questions on how SQL Server is licensed.
Which is better, FCIs or AGs?
Is one of these two technologies better than the other? Yes, almost certainly. But, which one? That’s really going to depend on what your objectives are, on what technologies and licenses you have in place or can afford, and on how your SQL Servers fit into the broader HADR conversation.
The important thing is to take the first step. Start having the conversations.
SQL Servers Healthy, Secure, And Reliable | Banking & Healthcare | Managing Partner of The SERO Group | DBA Team as a Service | Former 8-time Microsoft SQL Server MVP
3 年By the way - here's a link to the full article, if you'd like a bit more detail - https://theserogroup.com/sql-server/whats-the-difference-in-sql-server-fcis-and-ags