When we want to know if our databases are running well, most of us look at metrics for our servers. Usually some combination of CPU, RAM, Disk IO are chosen, though network, user connections, batches and transactions can be a part of tracking performance. I would guess if I asked any of you that are responsible for performance whatmight be a good measurement for your most important database server, you'd have some idea of what CPU, RAM, or something else should be running at. I know I can easily check on SQLServerCentral.com at monitor.red-gate.com and usually expect to see CPU in the 20-25% range. If it's substantially higher, I know something is going on.

I was listening to one of the DevOps Cafe podcasts recently where the subject was monitoring your infrastructure and how well it was performing. and one of the hosts mentioned listening to Werner Vogels from Amazon years ago. Apparently despite all the technical measurements that were available for Amazon's IT infrastructure, the one measure that they most often used to track how well everything was working was the order rate. Given their size and experience, Amazon could look at order rate and decide if their systems were performing well, both hardware and software.

Most of us might not be as tightly focused on our business, but I'm wondering if any of you use business based metrics when examining the performance of your hardware and software. Is there a metric for your business that might help you determine if your hardware is actually performing as expected? Or if your code does what the business needs in an application?

At SQLServerCentral, we have various ways of analyzing our systems, but we have added some business based metrics. One of those is forum posts/hour. We should see a similar curve throughout the week that shows how many posts we're getting. Across years of data, we have a fairly steady rate of posts that occur on a regular basis. If we're not getting a steady set of posts, we know something might be wrong.

Perhaps you don't have any business based metrics that you use, but are there any that might make sense for your industry? Let us know today. And if you think that there isn't a good way to measure your hardware and software with business metrics, I'd be interested in your explanation as well.

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The setting we want is SECONDARY. This will take backups on the secondary if it is running, but will take backups on the primary if that is the only node running.

There is no option for SECONDARY_PREFERRED.

Ref: ALTER AVAILABILITY GROUP - https://msdn.microsoft.com/en-us/library/ff878601.aspx

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