Articles by subject: Author: Edouard Haas

Why is FAT Slow on SD Card?

Edouard Haas October 17, 2024

This article discusses the performance limitations of the FAT file system with a focus on SD Card. After a brief refresher on FAT fundamentals, we show how FAT predictably achieves high access performances in the absence of fragmentation, but how fragmentation can build up until performances suddenly collapse. We conclude with a few important recommendations about the use of the FAT file system on embedded flash memory.

What Is a Flash File System?

Edouard Haas August 5, 2024

In this article, we explain how flash file systems achieve native support for raw flash devices. We compare flash file systems to a common alternative, which is the combination of a block device file system (e.g., FAT) with a flash translation layer (FTL), and we make the case that the native approach is a better overall solution.

Evaluating Embedded File System RAM Usage Under Real-Time Constraints

Edouard Haas April 3, 2024

In this article, we discuss the impact of real-time requirements on embedded file system performances and RAM usage. We show how to calculate the amount of buffering needed to absorb a hypothetical sequence of write accesses of varying duration. We show how RAM usage, write access time and average throughput are interdependent under our real-time assumption.

Making Sense of Flash File System Performances

Edouard Haas September 20, 2023

In this particular article, we show how the maximum average write throughput on a given flash device varies with the amount of stored data. We provide a simple performance model that can be used for setting realistic performance expectations, comparing file system performances, and questioning application requirements with minimal assumptions regarding the actual workload or file system implementation.

5 Things to Consider When Choosing an Embedded File System

Edouard Haas March 14, 2023

In this article, we cover five aspects of embedded file systems that you should have in mind when deciding which one to choose, five essentials that you can’t ignore. This is by no means a complete guide to embedded file systems but it covers enough to avoid common mistakes, particularly among application engineers who have little prior experience with embedded file systems.

Everspin MRAM Performance Benchmark Comparison

Edouard Haas November 7, 2022

For this article, we look at Everspin’s EM064LX in the context of data storage applications, focusing on access speed metrics, that is average throughput and worst-case access latency. For context, we compare MRAM performances with NOR and NAND flash using a simple benchmark and discuss the implications of the obtained results from an application design standpoint.

First Look at Everspin’s New xSPI STT-MRAM Lineup

Edouard Haas May 2, 2022

In this article, we take a closer look at this promising new offering, focusing on differentiating factors compared to existing flash-based devices and previous MRAM implementations. We present 4 use case scenarios to illustrate how we believe the EMxxLX xSPI family can compete with current flash-based solutions and how it really changes the game for us embedded designers.

Finding Flash a Successor

Edouard Haas March 31, 2022

This article is all about emerging non-volatile (NVM) technologies, a complex and ever-evolving topic that has stimulated numerous research fields over the years, and engaged substantial investments from the biggest players in the semiconductor industry. The topic is also quickly gaining momentum among embedded developers.

Uncovering SD card Performances using Bare-Metal Benchmarks

Edouard Haas October 24, 2021

In this article, we present a detailed discussion of SD card performances along with benchmarks for consumer and industrial-grade cards. The results help quantify the large variations in performance between individual devices and their impact on real-world performance.

The Case for Serial QSPI NAND in Deeply (And Not So Deeply) Embedded Applications

Edouard Haas September 30, 2020

QSPI NAND is a memory technology specifically designed as a direct alternative to its popular cousin, QSPI NOR. But what exactly is QSPI NAND? How does it compare to QSPI NOR? How does it compare to parallel NAND? This is what this article is all about.