SAFARI Project & Seminars Courses (Spring 2023)

NAND flash memory is the de facto standard for architecting a storage device in modern computing systems. As modern computing systems process a large amount of data at an unprecedented scale, a storage device needs to meet high requirements on storage capacity and I/O performance. A NAND flash-based solid-state drive (SSD) can provide orders-of-magnitude higher I/O performance compared to traditional hard-disk drives (HDDs), with a much lower cost-per bit value over SSDs based on emerging non-volatile memory (NVM) technologies.

NAND flash memory has several unique characteristics, such as the erase-before write property (i.e., a flash cell needs to be first erased before programming it), limited lifetime (i.e., a cell cannot reliably store data after experiencing a certain number of program/erase (P/E) cycles), and large operation units (e.g., modern NAND flash memory typically reads/writes data in a page (e.g., 16 KiB) granularity). To achieve high performance and large capacity of the storage system while hiding the unique characteristics of NAND flash memory, it is critical to design efficient SSD firmware, commonly called Flash-Translation Layer (FTL). An FTL is responsible for many critical management tasks, such as address translation, garbage collection, wear leveling, and I/O scheduling, which significantly affect the performance, reliability, and lifetime of the SSD.

In this course, we will cover how a modern NAND flash-based SSD is organized and operates, from the basics of underlying NAND flash devices and various SSD-management tasks at the FTL level. We will also examine other emerging memory technologies for building SSDs, such as Phase Change Memory, 3D XPoint (e.g., Intel Optane SSD) and more.

You will help build a practical SSD simulator by refactoring MQSim, a state-of-the-art simulator for high-end SSDs, to support advanced features of modern NAND flash chips and essential SSD-management tasks. This will allow you to have the chance to obtain a comprehensive background in modern storage systems and research experience on system optimization with rigorous evaluation.

Prerequisites of the course:

• No prior knowledge in NAND flash-based storage systems is required.
• Digital Design and Computer Architecture (or equivalent course)
• Good knowledge in C/C++ programming language is required.
• Interest in system optimizations

The course is conducted in English.

The course has two main parts: Weekly lectures on modern NAND flash-based SSDs and hands-on projects on storage systems and NAND flash memory.

Course description page Moodle

Spring 2023 Lecture Playlist

Recorded Lecture Playlist, Fall 2022

• Arash Tavakkol, Juan Gomez-Luna, Mohammad Sadrosadati, Saugata Ghose, and Onur Mutlu, "MQSim: A Framework for Enabling Realistic Studies of Modern Multi-Queue SSD Devices," In USENIX FAST, 2018.
• MQSim GitHub Repository

• Computer Architecture Fall 2020 - Lecture 26: Flash Memory and Solid-State Drives
• Computer Architecture Fall 2020 - Lecture 14: Simulation (with a Focus on Memory)

• Yu Cai, Saugata Ghose, Erich F. Haratsch, Yixin Luo, and Onur Mutlu, “Errors in Flash-Memory-Based Solid-State Drives: Analysis, Mitigation, and Recovery (Introduction and Section 1),” Invited Book Chapter in Inside Solid State Drives, 2018.
• Jisung Park, Myungsuk Kim, Myoungjun Chun, Lois Orosa, Jihong Kim, and Onur Mutlu, “Reducing Solid-State Drive Read Latency by Optimizing Read-Retry,” In ASPLOS, 2021.

• Arash Tavakkol, Mohammad Sadrosadati, Saugata Ghose, Jeremie Kim, Yixin Luo, Yaohua Wang, Nika Mansouri Ghiasi, Lois Orosa, Juan Gómez Luna, and Onur Mutlu, “FLIN: Enabling Fairness and Enhancing Performance in Modern NVMe Solid State Drives,” In ISCA, 2018.
• Bryan S. Kim, Hyun Suk Yang, and Sang Lyul Min,“AutoSSD: an Autonomic SSD Architecture,” In USENIX ATC, 2018.

• Aayush Gupta, Yongjae Kim, and Bhuvan Urgaonkar, “DFTL: A Flash Translation Layer Employing Demand-based Selective Caching of Page-level Address Mappings,” In ASPLOS, 2009.

• Jisung Park, Myungsuk Kim, Myoungjun Chun, Lois Orosa, Jihong Kim, and Onur Mutlu, “Reducing Solid-State Drive Read Latency by Optimizing Read-Retry,” In ASPLOS, 2021.
• Guanying Wu and Xunbin He, “Reducing SSD Read Latency via NAND Flash Program and Erase Suspension,” In USENIX FAST, 2012.
• Shine Kim, Jonghyun Bae, Hakbeom Jand, Wenjing Jin, Jeonghun Gong, Seungyeon Lee, Tae Jun Ham, and Jae W. Lee, “Practical Erase Suspension for Modern Low-latency SSDs,” In USENIX ATC, 2019.

• HW0 handout