Paper Details

Communicating Process Architectures (CPA)
 Title: A Real-time Garbage Collection Technique for Concurrent Flash Storage Architecture
 Conference: Communicating Process Architectures 2014
 Authors: Muhammed Ziya Komsul, Alistair A. McEwan
Department of Engineering, University of Leicester
 Abstract: Flash-based storage systems offer high performance, robustness, and reliability for embedded applications; however flash memory has limitations to its usage in high reliability applications. In previous work, we have developed RAID architectures and associated controller hardware that increase the reliability and lifespan of these storage systems by maintaining strict control over the lifespan of each chip in the array. However, flash memory needs regular garbage collection in order to reclaim its invalid spaces. When a garbage collector is active, the chip cannot be used by the application layer. This causes non-deterministic response time which is a problem for systems that require real-time guarantees. Recent techniques have been proposed to address the non-deterministic issue at single chip level; however effects of these techniques have not been investigated with concurrent flash architectures such as our RAID mechanism. We have applied a real time garbage collection technique over our RAID mechanism and observed that it affects strict control over the lifespan of the chips in the array. Thus, we have proposed an optimised real time garbage collector for our RAID mechanism. We evaluate our technique with a set of traces running on a software-based flash storage system simulator. 

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