CachedGC: Cache-assisted garbage collection in modern solid state drives

Narges Shahidi, Mahmut T. Kandemir

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Solid State Drives (SSDs) have many attractive features, and they are well-positioned to replace traditional HDDs in cloud and enterprise storages. However, some specific features they have such as erase-before-write and limited erase count make this transition more challenging. To tackle the issues brought by these features, Flash Translation Layer (FTL) leverages functionalities such as Garbage Collection (GC) to provide free space by erasing the blocks and cleaning the stale data. This process occupies SSD resources and causes extra waiting time for normal IO requests, and ultimately increases response time. Cloud workloads include many applications with small random write access patterns which cause frequent GC invocations. Flash occupation at the time of GC causes inconsistent performance and increases tail latency which may in turn violate SLA in these applications. In this paper, we modify the conventional GC process and propose a Cache-Assisted Garbage Collection (CachedGC). CachedGC postpones writing back valid pages during the GC, erases the block at the first possible time, and hence resumes normal SSD operations sooner. CachedGC reduces request response time and tail latency by reducing the effective latency of GC. Our experimental results using a variety of workloads show that CachedGC reduces read tail latency by 19% and improves write IOPS by as much as 27%.

Original languageEnglish (US)
Title of host publicationProceedings - 26th IEEE International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems, MASCOTS 2018
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages79-86
Number of pages8
ISBN (Electronic)9781538668863
DOIs
StatePublished - Nov 7 2018
Event26th IEEE International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems, MASCOTS 2018 - Milwaukee, United States
Duration: Sep 25 2018Sep 28 2018

Publication series

NameProceedings - 26th IEEE International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems, MASCOTS 2018

Other

Other26th IEEE International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems, MASCOTS 2018
CountryUnited States
CityMilwaukee
Period9/25/189/28/18

All Science Journal Classification (ASJC) codes

  • Computer Networks and Communications
  • Modeling and Simulation

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  • Cite this

    Shahidi, N., & Kandemir, M. T. (2018). CachedGC: Cache-assisted garbage collection in modern solid state drives. In Proceedings - 26th IEEE International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems, MASCOTS 2018 (pp. 79-86). [8526873] (Proceedings - 26th IEEE International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems, MASCOTS 2018). Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/MASCOTS.2018.00015