IOPS Calculator
Use this IOPS calculator to estimate whether a storage set has enough random I/O capacity for a workload after accounting for read/write mix and RAID write penalty.
Calculator
How to use this calculator
Enter the planning values that match your network, storage, or cloud scenario. Use realistic production assumptions when sizing anything that affects availability, performance, or cost.
Formula or calculation method
Reads are counted once, while writes are multiplied by the RAID write penalty. Estimated capacity blends drive read IOPS and write IOPS according to the workload mix.
Worked example
A 5,000 IOPS workload with 70% reads and RAID 5 style penalty of 4 needs about 9,500 physical I/O operations after write penalty.
Practical planning tips
- Storage sizing.
- VM datastore planning.
- RAID tradeoff estimates.
Common mistakes to avoid
- Ignoring write penalty.
- Using sequential throughput numbers as random IOPS.
- Forgetting latency, cache, queue depth, and real workload patterns.
Frequently asked questions
What RAID penalty should I use?
Common rough values are 2 for mirrors, 4 for RAID 5, and 6 for RAID 6, but storage systems vary.
Is this enough for production sizing?
Use it for early planning, then validate with vendor guidance and real workload metrics.