Who makes hdd for AI data centers

HDD sits below NAND and enterprise SSDs (2.07, 2.08) in the storage hierarchy, typically inside the AI storage systems described next (2.10) as the capacity tier for raw and processed datasets, backups, and object stores rather than the latency-critical path a GPU reads from directly. The volume of training data, checkpoints, and generated content that needs affordable long-term retention keeps growing even as flash takes over the performance-sensitive tiers, which sustains nearline HDD demand alongside SSD growth rather than being displaced by it. For an investor, this is a consolidated supplier base of a small number of large-scale drive makers where areal-density roadmaps and qualification with the largest buyers gate competitive position, and the category competes for the same underlying manufacturing investment dollars against flash's continued growth.