Azure database utilisation (DTUs)

Question

I'm looking at the usage of an Azure SQL database (standard S2 instance, 50 DTUs) and I want to make sure I understand DTUs correctly.

The chart below shows both the monthly DTU limit (green line) and DTUs used (orange line) over the last 30 days.

My original understanding of DTUs was that they were discrete resource units that could be consumed (e.g. perform N IOPS and use up one DTU), but from this chart it looks like a DTU is a metric of the level of overall performance allocated to the database.

Am I correct in saying that the utilisation of this database is very low (around 2% on average)?

Answer 1

Database Transaction Units (DTUs)

The Database Transaction Unit (DTU) represents a blended measure of CPU, memory, reads, and writes. The DTU-based purchasing model offers a set of preconfigured bundles of compute resources and included storage to drive different levels of application performance.

So it is a quota, based on a benchmark, indexed by several resources. Good for comparing Azure SQL offerings relative to each other with one number. Bad for anything not-Azure as the formula is proprietary and not public. (But of course people have had fun with the calculator.)

2% is low utilization of CPU/memory/IOPS, so it is low for DTUs. What exactly this means to you is a capacity planning exercise. Perhaps it is a tiny toy database that can be resized to the most basic offering, perhaps it is sized to handle a load spike, perhaps it is not being used (yet).