Setup If you’re using availability groups with read-scale or linux (cluster type = None/External), you might want to watch the number of databases put into a single availability group. There seems to be an issue where having a very large number (~200) of databases in an AG works without issue, however going higher may result […]
I was recently asked a question, while fixing a cluster connectivity issue, about how the cluster resource dll knows on which port to connect to SQL Server. It’s not a very exciting answer, which is, “It doesn’t.”. After some days passed I was thinking about the question and answer as though the response I had […]
I see many questions, and have been on the receiving end of many myself, about out of support items and removing them from their SQL Server servers. One of these items is the SQL Server Native Client, aka SNAC, aka SQLNCLI, and I’m sure many others. I remember investigating the connections a very long time […]
Many DBAs haven’t had the experience of using database mirroring, since it was deprecated in 2012 when availability groups were released, and so there’s a lot of history that ends up being lost. We’re going to dive into some of that history and how it could affect your availability group! Update: You can get rid […]
Initially I thought to myself, “this is the most misunderstood wait type that exists in the HA space for SQL Server”, then I realized maybe this isn’t the case… So, I pondered over this question, “is it truly misunderstood?” and came to the (possibly incorrect) realization that it is quite accurate in the general SQL […]
Overall Introduction I’ve had some feedback that people would like to know some of the stuff I see and how I ended up finding the issue and troubleshooting the problem. I present to you a new heading/series called “olved steries”. If you’re wondering, “What is this name and do you not know how to spell?” […]
One of the most common issues I look at from day to day is some variation of the question. “Why did it take a long time for my AG/Database to failover?”. There are many different meanings for this innocuously simple looking statement, for example was it that the failover time was long or was it […]
I tend to be involved in many HA related issues, as is the nature of my current work agreement. The interesting part is that roughly 85% of all the “HA” issues are performance issues (with 10-12% being config issues and the last 3-5% being truly HA issues). Whether this is an FCI, AG, Replication, some […]
On, Off, On, Off, On… I see this more often than I’d like to, so count this as your PSA (public safety announcement) when using VM level backup software, SQL Server, and even worse when you add in AlwayOn (FCI or AG). You might be familiar with these symptoms which may include: Unresponsive VMs Lease […]
I won’t say I told you so… I will, however, point out common AG question #8… I’m not sure why so many of these are coming up lately, but I’ve not had to troubleshoot a few, and I think it’s worth documenting this behavior. Let’s say you have Windows cluster which might have FCI’s, AG’s, […]
