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Unveiling the Secrets of Azure Event Hubs: A Guide to Capacity Planning

6 Min. Read

A critical phase in developing a system or application is ensuring the infrastructure can gracefully handle anticipated loads and traffic while staying within predefined limits. Azure Event Hubs, is a highly scalable data streaming platform crucial for real-time data analysis and integration. Capacity planning stands as a crucial phase in the development of any system or application.

In this article, we explore Azure Event Hubs’ capacity planning for seamless integration and real-time analysis. We delve into the intricacies of capacity planning, focusing on the Azure Event Hubs, a robust data streaming platform. We learn about tiers, throughput, and benchmark tools to optimize your solution effortlessly.

Understanding Azure Event Hubs Properties

Before delving into capacity planning, let’s understand the key components of Azure Event Hubs. One noteworthy component is the Event Hub itself, a highly scalable data streaming platform designed for real-time data analysis.

Azure Event Hubs offers four tiersBasic, Standard, Premium, and Dedicated. These tiers not only differ in scale capacity and limits but also in features like availability, throughput units, auto-inflate, retention period, and of course, pricing. Choosing the right tier is a pivotal aspect of effective capacity planning.

Azure Event Hubs pricing
Azure Event Hubs [Microsoft Azure pricing page]
Each tier enables you to specify the amount of throughput by using a certain number of units. Although the name of the unit type differs between tiers, it carries the same meaning of defining the capacity of your namespace for both incoming and outgoing messages. This capacity is measured in terms of the number of messages per second and the size of data per second that your namespace can handle.

Azure Event Hubs allows you to effortlessly capture real-time data streams in an Azure Blob storage or Azure Data Lake Storage Gen 1 or Gen 2 account of your preference. You can choose to specify a time or size interval, which gives you more flexibility and control over your data.

Understanding Azure Event Hubs Features
Understanding Azure Event Hubs Features

The number of partitions is a crucial factor to consider when planning the capacity of a system. This is because it affects the level of concurrency. If you do not utilize batching and have N partitions, you will only be able to process N messages simultaneously.

Related: Enable Azure Resource Diagnostic Settings to Event Hub using Azure Policy.

Steps for Azure Event Hubs Capacity Planning

Let’s go through all the steps that you should take to conduct capacity planning for Event Hubs:

Step 1: Analyzing Applicative Requirements

To ensure optimal performance, it’s imperative to analyze applicative requirements. This includes determining the number of Event Hubs needed, consumer group count, message processing order, and tolerance to data loss and duplication.

In this step, you need to ask the following questions:

How many Event Hubs would you like to use for your flow?
Do you have one consumer of the message or more — number of consumer groups?
Do you need to process messages by order? Processing messages in order is not supported by Event Hub, making it an unsuitable solution.
Do you need some messages to be processed “together” (by the same consumer)? Using the partition key, messages can be processed together by the same consumer.
How tolerant are you to data loss?
How tolerant are you to message duplication?
What is the maximum allowed latency for processing? The maximum allowed time since the message is sent to the Event Hub and until it is received to be processed.

Related: Create an Event Hub Namespace with Azure PowerShell.

Step 2: Evaluating Non-Functional Requirements

Delving into non-functional requirements involves assessing expected throughput, growth rates, message sizes, and processing duration distributions. Infrastructure considerations, including location and reliability levels, must align with the overall system architecture.

In this step, you look at the following:

# What is the throughput you expect — for each event hub in the namespace and both Ingress and Egress:

  • Is it stable/what are the spikes?
  • What is the growth rate?

# What is the message size:

  • The range of message sizes
  • What is the distribution of sizes?
  • What is the maximum size you expect?

# Processing Duration:

  • What is the distribution (percentiles) of processing durations?

# Infrastructure consideration:

  • What is the location (region) — of the event hub namespace/the consumers/the producers?
  • Reliability level — Multi-AZ/Geo redundancy ext.

Step 3: Choosing the Right Tier and Properties

By going through Step 1 and Step 2 above, you could have a good estimation of which properties of the event hub you need. Selecting the appropriate tier involves considering applicative and non-functional requirements. Basic, Standard, Premium, or Dedicated tiers offer distinct features, impacting system performance and cost.

Please note that certain decisions cannot be modified after creating a namespace. In such cases, it may be necessary to create a new namespace and migrate, such as in the case of Tier selection.

Understanding throughput in terms of messages per second and data size is pivotal. Each tier allows defining throughput using different units, influencing the capacity for both ingress and egress. Check the Azure Event Hubs quotas and limits.

Event Hubs Namespace Scale Settings
Event Hubs Namespace Scale Settings

Partition count significantly influences concurrency. Effective capacity planning requires a thoughtful analysis of partition count, especially in scenarios without batching.

Step 4: Executing a Benchmark for Accurate Results

Calculating the required throughput and limits can provide an estimate, but it can be difficult to account for all factors, particularly in complex architectures – such as a namespace containing multiple event hubs with significant numbers of consumer groups.

Since calculations provide estimates, running a benchmark is crucial for accurate results. The recommended approach is to run a dedicated benchmark tool that will explore the significance of benchmarking and its role in assessing system limits.

Running a benchmark involves simulating load to uncover system limitations. You could use a dedicated benchmark tool like Event Hubs Throughput Test published by Oshvartz
that ensures a comprehensive evaluation.

This tool is a simple using dotnet CLI that can help you simulate the load on the Event Hub namespace. Its parameters allow you to first build your use case and then alter some parameters to optimize performance such as:

  • Prefetch count
  • Max batch size

Sometimes, it may be necessary to run multiple benchmark processes simultaneously to accommodate various event hubs under the same namespace.

Step 5: Assessing Benchmark Results

Post-benchmark, validating decisions is imperative. Assessing whether the system meets current load needs and understanding its limits helps refine the chosen configuration.

To ensure scalability, you need to consider growth rates post-benchmark that help gauge future scalability. Flexibility in adjusting configurations becomes crucial for accommodating increased demands.

If the benchmark result does not meet your requirements, you may need to revisit previous steps.

Frequently Asked Questions (FAQs)

Why is partition count crucial in Event Hub capacity planning?

Partition count directly impacts concurrency, influencing the system’s ability to process messages simultaneously.

What are Event Hub throughput units?

Event Hubs uses “throughput” to measure the amount of data that enters and exits the system. This is measured in “throughput units” (TUs). You need to purchase TUs before using the service and can choose them explicitly in the portal or by using templates.

Throughput units (TUs) are billed on an hourly basis. The billing is based on the maximum number of units that were selected during the given hour.

How can I optimize the usage of my throughput units?

You can start with as little as one throughput unit (TU) and activate the auto-inflate feature to automatically increase your TUs as your traffic/payload grows. You can also set an upper limit on the number of TUs.

Can I modify Event Hub properties post-namespace creation?

Certain decisions, like tier selection, are irreversible post-creation. In such cases, creating a new namespace and migrating may be necessary.

What factors should I consider in non-functional requirements for Event Hubs?

Non-functional requirements include expected throughput, growth rates, message sizes, processing duration distributions, infrastructure considerations, and cost.

Why is benchmarking not an optional step in Event Hub capacity planning?

Benchmarking provides real-world insights into system performance and helps identify limitations that may not be evident through calculations alone.

Is Azure Event Hub the same as Kafka?

While Azure Event Hubs share similarities with Kafka, they are distinct platforms. Event Hubs is a fully managed service in Azure, whereas Kafka is an open-source distributed event streaming platform.

What is the difference between Azure Monitor and Event Hub?

Azure Monitor is a comprehensive monitoring solution, whereas Azure Event Hubs is a data streaming platform. Azure Monitor provides insights into the performance and health of various Azure services, while Event Hubs focuses on real-time event processing.


In this article, we discussed all the steps to properly perform Azure Event Hubs’ capacity planning for seamless integration and real-time analysis. We learned about the different tiers, including throughput, and benchmark tools to optimize your event processing solution.

Capacity planning is a critical aspect, especially for complex systems like Azure Event Hubs. Early planning significantly impacts the solution and infrastructure. The steps outlined in this guide apply to various infrastructure components, emphasizing the importance of meticulous planning in development.

Thank you for reading my blog.

If you have any questions or feedback, please leave a comment.

-Charbel Nemnom-

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About the Author:
Charbel Nemnom
Charbel Nemnom is a Senior Cloud Architect with 21+ years of IT experience. As a Swiss Certified Information Security Manager (ISM), CCSP, CISM, Microsoft MVP, and MCT, he excels in optimizing mission-critical enterprise systems. His extensive practical knowledge spans complex system design, network architecture, business continuity, and cloud security, establishing him as an authoritative and trustworthy expert in the field. Charbel frequently writes about Cloud, Cybersecurity, and IT Certifications.

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