Subscription Ratios in OpenStack: A Quick Guide for IT Leaders

In this blog

• What Are Subscription Ratios in OpenStack?
• Why Are Subscription Ratios Important?
• Mastering the Art of OpenStack Subscription Ratios: Tips and Best Practices
• Wrapping Up: Subscription Ratios in OpenStack

OpenStack is undeniably a powerful and versatile cloud platform that many industries continue to adopt at an increasing rate. Obviously, we’re big fans! But, like any intricate technology, having a firm understanding of its inner workings is crucial for deriving maximum efficiency, especially if your business provides cloud or primarily online services. So today, we’ll be diving into the world of subscription ratios in OpenStack, which play a vital role in resource allocation across your infrastructure.

What Are Subscription Ratios in OpenStack?

OpenStack subscription ratios are essential for optimal allocation of physical resources. In essence, they determine how much capacity you can provision to virtual machines (VMs) based on how much physical capacity is available through your computes (also known as your hypervisors). By thoughtfully setting ratios, you can balance your infrastructure’s performance, workload capacity, and overall efficiency.

Subscription ratios denote the relationship between the total resources on a compute node and the actual usable capacity for instances. This concept is pivotal in resource allocation and helps us strike the perfect balance between optimizing our resources and ensuring efficient utilization.

Fun fact: The term ‘subscription ratio’ stems from the academic world, where it’s used to express the ratio between the number of students and available classroom resources.

Mastering the Art of OpenStack Subscription Ratios: Tips and Best Practices

In OpenStack, there are two key ratios to consider: CPU and RAM. Understanding these ratios paves the way for better resource utilization, leading to an overall enhanced experience. It also mitigates challenges such as over commitment, thereby ensuring a seamless and stable environment for your cloud-based endeavors.

Subscription ratios are usually set for three core resources: CPU, RAM, and Disk. The default ratios in OpenStack are: CPU: 16.0, RAM: 1.5, and Disk: 0.0. Interestingly, the Disk ratio is set to zero by default since I/O performance is often harder to predict and typically configured manually based on your specific use cases.

Fun fact: The RAM ratio stems from an assumption that, on average, VMs use 66% (1/1.5) of allocated memory!

How Do You Set the Right OpenStack Subscription Ratios?

Setting the right ratios is more an art than a science. It starts with a deeper understanding of your business requirements and workloads, awareness of application behavior, and a good grasp of the physical infrastructure at hand.

To help identify the best ratios, consider the following pointers:

1. Study your current workloads: Analyze peak and off-peak loads to ensure you’re provisioning for both to ensure your infrastructure runs smoothly.
2. Benchmark your infrastructure: Test current and anticipated workloads under different ratios and identify bottlenecks. A well-executed trial-and-error approach will help fine-tune ratios.
3. Overbooking resources: For some workloads, you may decide to overbook resources, going beyond their physical limitations. While this may save costs, it’s no secret that it could lead to performance degradation in certain scenarios. Tread carefully!
4. Don’t forget to monitor: Regularly review your resource utilization and make adjustments when needed. Cloud infrastructures are dynamic in nature, and your ratios should be dynamic as well. Striking the right balance between resource allocation and performance largely depends on insightful subscription ratio management.

Wrapping Up: Subscription Ratios in OpenStack

So, there you have it, friends! By being mindful of your subscription ratios in OpenStack, you can ensure that your cloud infrastructure runs at its best capacity while delivering excellent performance. Happy cloud managing!