Welcome to the Microsoft Q&A forum.
For your first question:
Yes, The cluster(IR) used in the debug session is different from the one specified in the dataflow integration runtime
(Or) You can use the same IR on the "dataflow debug" session.
When you enable "dataflow debug", You will be charged on that particular IR for the duration.
When you turn on "Data flow Debug" on the integration runtime drop-down, you can choose one of the existing IRs you already created.
If you choose the debug time to live = 4 hours for a small cluster, you will be charged for the 4 hours on that IR.
So your charge on the "dataflow debug" is as follows:
small cluster = 8 Vcores
total time = 4 hrs
1 debug session = 1 instance
total cost = 1 instance * 4 hours
Considering your cluster is using basic V-cores, then the cost would be = $8.74 (for the dataflow debug session)
My understanding is Basic Vcores are used on the auto IR. (but this is not documented). The billing team can confirm this if you need more details on it.
For your question on the document:
"Nodes" in the document is nothing but the cluster size( small, medium, large etc)
Small node = 4 driver nodes + 4 worker nodes = 8 Vcores
Coming to IR on the dataflow:
You can also choose the existing IR from the drop-down or create a new IR here. IR is nothing but compute to run the activities.
The price varies depending on the IR size- small, medium, large etc. Small nodes have fewer Vcores compared to medium or large nodes.
The same above formula applies to the Dataflow IR as well.
Ex: If your data flow ran for 4 hours with a small cluster, the price would be the same as above.
So, the total price for the dataflow IR = cost of the IR on the "dataflow debug" + cost of the IR on the actual dataflow to run the activities.
Here, I am considering a different IRs on the "dataflow bebug" and the actual dataflow.
If you use the same cluster, the compute will be shared between the dataflow debug and the dataflow to run the activities.
Please note: The minimum vcores for IR is 8
Data Flows are visually-designed components that enable data transformations at scale. You pay for the Data Flow cluster execution and debugging time per vCore-hour. The minimum cluster size to run a Data Flow is 8 vCores. Execution and debugging charges are prorated by the minute and rounded up.
I hope this helps. Please let me know if you have any further questions.
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