Typically, the size of the IoT Hub is decided by the number of messages that are being sent by the IoT devices in one day.
Here is an IoT Hub instance size table:
|
Tier |
Sustained throughput |
Sustained send rate |
|
S1 |
Up to 1111 KB/minute per unit (1.5 GB/day/unit) |
Average of 278 messages/minute per unit
|
|
S2 |
Up to 16 MB/minute per unit
|
Average of 4167 messages/minute per unit (6 million messages/day per unit) |
|
S3 |
Up to 814 MB/minute per unit
|
Average of 208,333 messages/minute per unit (300 million messages/day per unit) |
Now let's take an example of how we are supposed to think about calculating the required IoT Hub size based on our deployment of IoT devices.
Consider a scenario where there are 10,000 IoT devices, which send data every second. What tier should you use and how many units? You need to send 10,000 messages per second so three units of S3 will suffice. You can also take 142 units of S2 for the same performance and price.
While this sample calculation will give you an understanding of how we should select the IoT Hub size, this is a very important design step when you are working on a very large number of IoT device solutions. if at the time of designing the solution these points are not considered the result could be a throttling of messages sent to the IoT Hub.