Is It Safe to Lower EBS Provisioned IOPS and Throughput Below Instance Baselines?

Overview

When optimizing AWS costs, CloudFix may recommend lowering the provisioned IOPS and throughput on your Amazon EBS (Elastic Block Store) volumes-even below the baseline performance documented for your EC2 instance type. This article explains what this means, when it is safe, and how to ensure your workload remains healthy.

What Are EBS-Optimized Instances and Baselines?

• EBS-optimized instances provide dedicated bandwidth for EBS I/O, ensuring consistent performance by isolating EBS traffic from other network activity.
• Each EC2 instance type has a documented baseline and maximum EBS performance (measured in IOPS and throughput).
  • Baseline = The level of performance the instance can sustain indefinitely.
  • Maximum = The highest performance possible, often only available in short bursts.

What Happens If You Lower Provisioned IOPS/Throughput?

• The provisioned IOPS/throughput of an EBS volume sets the maximum performance that volume can deliver.
• Your application’s actual performance will be limited by the lowest of:
  • The provisioned IOPS/throughput on the EBS volume,
  • The EC2 instance’s baseline or maximum EBS performance,
  • The actual demand of your workload.
• If you provision less than the instance’s baseline:
  • The EBS volume becomes the bottleneck, but only if your workload tries to exceed the new, lower limits.

Why Does CloudFix Recommend Lowering Provisioned IOPS/Throughput?

• CloudFix analyzes your real-world EBS usage (via CloudWatch metrics).
• Recommendations to lower provisioned IOPS/throughput are made only when your actual usage is consistently well below what you’ve provisioned.
• CloudFix ensures a buffer above your observed peak usage to avoid performance impact.

Is Lowering Provisioned IOPS/Throughput Harmful?

No, it is not harmful-as long as your workload does not require more performance than what you have provisioned.
Potential risks:

• If your workload spikes above the new provisioned limits, you may see increased latency or throttling.
• If you set provisioned IOPS/throughput below your actual peak demand, performance will degrade.

Best Practices

1. Monitor Your Workload:
   Use CloudWatch metrics to track actual IOPS and throughput usage, as well as latency and queue length.
2. Right-Size with Headroom:
   Set provisioned IOPS/throughput to cover your peak observed usage, plus a safety buffer.
3. Review Regularly:
   Reassess your EBS provisioning as workloads change over time.
4. Respond to Alerts:
   Set up CloudWatch alarms for latency or queue depth to catch any performance issues early.

Conclusion

Lowering EBS provisioned IOPS and throughput below the instance baseline is a safe and effective cost optimization-if your workload does not require the higher performance. Always monitor your usage and leave headroom for unexpected spikes. Cost optimization should never come at the expense of application reliability.

References

• AWS EC2 EBS-Optimized Instances Documentation