SSD Simulator
Learn SSD

Understand SSDs from the ground up

A plain-English, illustrated guide to everything happening inside a solid-state drive — and everything you need to read the EyanaSSDSim paper. No prior background assumed. Read top to bottom as a course, or jump to any topic.

Start reading → Open the Live Simulator

Foundations
01 Foundations
What Is an SSD? Flash Memory vs. Hard Drives

Why solid-state drives behave so differently from the spinning disks they replaced.
02 Foundations
Inside the Chip: Cells, Pages, Blocks, Planes, Dies, Channels

The physical hierarchy of a flash SSD — and why every level exists.
03 Foundations
The Big Asymmetry: Read, Program, and Erase

Why writing to an SSD is never as simple as it sounds.
The FTL at Work
04 The FTL at Work
The Flash Translation Layer (FTL) and Address Mapping

The tiny operating system inside every SSD that hides flash's quirks.
05 The FTL at Work
Garbage Collection: Cleaning Up Stale Data

How the SSD reclaims space — and why it can never be free.
Performance & Endurance
06 Performance & Endurance
Write Amplification (WAF): The Hidden Write Tax

Why writing 1 GB to an SSD can cost it 2 GB of real flash writes.
07 Performance & Endurance
Over-Provisioning: Spare Space That Buys Performance

The hidden capacity that keeps garbage collection cheap.
08 Performance & Endurance
Endurance, Wear, and Wear Leveling

Flash cells wear out — the trick is to make them wear out evenly.
09 Performance & Endurance
Measuring Wear Evenness: CV, Gini, and Fourier

Turning a cloud of erase counts into a single, comparable number.
Advanced
10 Advanced
Data Placement & Allocation Schemes (S1–S6)

Which channel, die, and plane should each write go to? It matters more than you'd think.
11 Advanced
Zoned Namespaces (ZNS): Giving the Host Control

A newer kind of SSD that trades convenience for dramatically lower write amplification.
The Paper
12 The Paper
How EyanaSSDSim Models All of This

Tying every concept together — and how to read the paper and use the simulator.

These posts accompany the EyanaSSDSim simulator and paper. Concepts are introduced in reading order; each post links to the related ones and to the live tool where you can see it in action.