SSD (Solid State Drive)

An SSD (Solid State Drive) is a storage device that holds data in NAND flash memory cells rather than on magnetic platters. Because nothing spins and nothing moves, an SSD serves a random read in tens of microseconds — roughly a hundred times faster than a mechanical drive — while consuming less power, generating no noise and shrugging off vibration that would damage a hard disk.

How an SSD works

Every SSD is built around a controller, a dedicated processor that orchestrates the flash chips. Flash memory cannot be overwritten in place: a whole block must be erased before new data lands in it. The controller therefore maintains a mapping between logical addresses and physical cells, spreads writes evenly to prevent premature wear (wear leveling), consolidates half-empty blocks in the background (garbage collection) and honours the TRIM command so the operating system can flag deleted data. Cell types — SLC, MLC, TLC and QLC — trade endurance for density: more bits per cell means cheaper storage but fewer write cycles.

Connectivity determines the ceiling. SATA SSDs are limited to about 550 MB/s by the interface itself, while drives using the NVMe protocol over PCIe reach several gigabytes per second and, more importantly, sustain hundreds of thousands of IOPS thanks to deep command queues.

Practical applications

Flash storage is the default wherever latency shapes the user experience:

• boot and application volumes on servers and workstations,
• relational databases dominated by small random reads and writes,
• web and e-commerce hosting, where storage latency feeds directly into page load times,
• caching layers, message queues and CI build agents.

For server workloads, two datasheet figures deserve more attention than headline throughput: TBW (total bytes written, the endurance rating) and power-loss protection, which guarantees that in-flight writes survive a sudden outage. A VPS backed by SSD or NVMe storage will feel dramatically snappier than the same instance on HDDs, because every dynamic page request triggers dozens of small disk operations — exactly the pattern flash memory handles best.