HDD · hard disk drive
Rotating magnetic disk storage, now confined to the cold capacity tier and notable operationally because it cannot be immersion-cooled and is sanitized differently than flash.
Current numbers
~$36BAI storage market (2025), ~24% CAGR; QLC + data reduction displacing HDD across hot and capacity tiers
~7 GB/s vs ~300 MB/sQLC SSD vs HDD sequential read; 20–100 µs vs ~4 ms latency