What s Actually Happening Inside Your SSD

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About the video:

Your brand new SSD hits 500,000 random reads per second. Six months later, write speeds drop and latency spikes appear. The drive isn't broken — it's doing exactly what it was designed to do.

In this video, I break down everything happening inside your SSD: how NAND flash stores bits using floating gates, why you can write pages but only erase blocks, how the Flash Translation Layer maps logical to physical addresses, how garbage collection reclaims space (and causes write amplification), how wear leveling and TRIM keep your drive healthy, and why SLC, MLC, TLC, and QLC make different tradeoffs.

To run smartctl commands on Windows, install https://smartmontools.com/ first.

Timestamps:
0:00 — Why your SSD slows down
0:20 — Hard disk drives vs SSDs
1:00 — Inside the SSD: controller, DRAM, NAND
2:31 — How NAND stores a bit (floating gates)
4:29 — Pages and blocks: the rules of NAND
7:01 — The update problem
8:20 — Flash Translation Layer (FTL)
10:20 — Garbage collection and write amplification
12:18 — Wear leveling and TRIM
14:27 — SLC, MLC, TLC, QLC explained
15:40 — Practical takeaways
16:32 — Outro