I had a request from a customer recently who asked if we could give them a report of their database server instances and include CPU usage. This request was filtered through an account executive, so something was lost in translation, but I was confused and asked for clarification, as asking for CPU usage is kind of like asking how fast you were traveling in your car. There needs to be more context.
If someone asked you for a report of CPU usage for a database, what would you expect? How would you report this? I’m sure the person asking might make a difference. A fellow DBA, your DBA manager, or maybe an executive could all view this differently. I want to know how things are performing, if there is a trend, or maybe if we are getting value for the hardware we’ve provisioned, depending on my role.
If you were looking at your monitoring system, what would you look for? Redgate Monitor shows the last 24 hours of CPU with the last two hours in a focus window as the default, though you can easily change this. Perhaps you’d prefer this boiled down to min/max/average values over a time period? If there’s something else you’d consider, let me know. Maybe I can get it added.
Certainly, the values you expect might depend on what you are trying to measure. Is there an acute performance issue? Then you might worry about the spot values or perhaps the last xx minutes of trending CPU values. If this is capacity planning, then peaks and average values can matter. If you are looking forward, you might even want longer trend lines and future extrapolation.
Of course, the experienced DBA knows that other metrics need to be taken into account when looking at the CPU. 100% usage isn’t necessarily an issue if the workload isn’t creating unnecessary processes stacking up or too much latency in returning results. Perhaps the amount of memory used should be included to determine if there are CPU or RAM (or other) bottlenecks.
There are a lot of factors that might go into how you examine the performance or efficiency of a database server, whether SQL Server or any other platform. A well-performing system has to balance lots of factors to meet the demands of a workload. A poor-performing system doesn’t do this well and often there are many more factors than how much of your CPU capacity is being used.
The other thing this request showed me is how poorly many people communicate, and especially how much can be lost as a message moves from one person to another. This is an area where AI can succeed or fail as well. IF we communicate poorly with AI, we may waste time and money while receiving useless results. If we let AIs provide summaries to us, or from us, the model may choose to emphasize, highlight, reword, or hide things we think are important. After all, the model is predicting what should come next, not understanding the information.
Communication is crucial and is becoming more important as we become more distributed and allow technology to sit between us.
Steve Jones
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Voice of the DBA 