For a customer planning to upgrade their HF40 controllers to support additional I/O requirements, upgrading to the HF60 (Option C) is the recommended path. The HPE Nimble HF60 offers enhanced performance, greater scalability, and improved I/O capabilities compared to the HF40. This upgrade ensures that the storage array can handle more demanding workloads and support future growth. The HF60 model is designed to meet the needs of environments requiring higher performance and capacity, making it suitable for customers looking to expand their infrastructure without a complete overhaul. Reference: HPE Nimble Storage Solutions HPE Nimble Storage Controller Upgrade Path