SSDs: Solid-State Drives That Replaced Spinning Disks
SSDs store data in NAND flash memory with no moving parts, delivering dramatically faster performance than HDDs — connected via SATA (~550 MB/s) or NVMe/PCIe (3,500-7,000+ MB/s).
Solid-state drives (SSDs) store data in NAND Flash Memory: How Solid-State Storage Stores Data in Trapped Electrons with no moving parts. Compared to traditional hard disk drives (HDDs), SSDs offer dramatically faster random access (no seek time), higher throughput, greater shock resistance, lower power consumption, and silent operation. ## Interfaces - **SATA: The Serial ATA Interface for Storage Devices** SSDs: Use the AHCI: The Storage Interface That Became a Bottleneck for SSDs protocol, limited to ~550 MB/s — the interface is the bottleneck, not the flash - **NVMe: The Storage Protocol That Replaced SATA for High-Performance Drives** SSDs over PCIe: Purpose-built protocol for flash, achieving 3,500–7,000+ MB/s sequential and hundreds of thousands of IOPS ## NAND Types Consumer SSDs use TLC (3 bits/cell) or QLC (4 bits/cell) flash for density and cost. Enterprise SSDs may use MLC (2 bits/cell) or TLC for better endurance. Write cycles are finite, but modern wear-leveling and over-provisioning make SSD lifespan a non-issue for typical consumer use. ## Market Position SSDs have largely replaced HDDs for boot drives and primary storage in laptops, desktops, and servers. HDDs persist for bulk cold storage and archival where cost per terabyte matters — HDD pricing (~$15/TB) remains well below SSD (~$50-80/TB as of 2026). **See also:** Flash Memory Data Retention: Why Unpowered Storage Loses Data