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Title: A Semi-Preemptive Garbage Collector for Solid State Drives

Abstract

NAND flash memory is a preferred storage media for various platforms ranging from embedded systems to enterprise-scale systems. Flash devices do not have any mechanical moving parts and provide low-latency access. They also require less power compared to rotating media. Unlike hard disks, flash devices use out-of-update operations and they require a garbage collection (GC) process to reclaim invalid pages to create free blocks. This GC process is a major cause of performance degradation when running concurrently with other I/O operations as internal bandwidth is consumed to reclaim these invalid pages. The invocation of the GC process is generally governed by a low watermark on free blocks and other internal device metrics that different workloads meet at different intervals. This results in I/O performance that is highly dependent on workload characteristics. In this paper, we examine the GC process and propose a semi-preemptive GC scheme that can preempt on-going GC processing and service pending I/O requests in the queue. Moreover, we further enhance flash performance by pipelining internal GC operations and merge them with pending I/O requests whenever possible. Our experimental evaluation of this semi-preemptive GC sheme with realistic workloads demonstrate both improved performance and reduced performance variability. Write-dominant workloadsmore » show up to a 66.56% improvement in average response time with a 83.30% reduced variance in response time compared to the non-preemptive GC scheme.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [2]
  1. ORNL
  2. Georgia Institute of Technology
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). National Center for Computational Sciences (NCCS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1017323
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: IEEE International Symposium on Performance Analysis of Systems and Software (ISPASS), Austin, TX, USA, 20110410, 20110412
Country of Publication:
United States
Language:
English
Subject:
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; EVALUATION; METRICS; PERFORMANCE; PROCESSING; STORAGE; Flash Memory; Storage Systems; Garbage Collection

Citation Formats

Lee, Junghee, Kim, Youngjae, Shipman, Galen M, Oral, H Sarp, Wang, Feiyi, and Kim, Jongman. A Semi-Preemptive Garbage Collector for Solid State Drives. United States: N. p., 2011. Web.
Lee, Junghee, Kim, Youngjae, Shipman, Galen M, Oral, H Sarp, Wang, Feiyi, & Kim, Jongman. A Semi-Preemptive Garbage Collector for Solid State Drives. United States.
Lee, Junghee, Kim, Youngjae, Shipman, Galen M, Oral, H Sarp, Wang, Feiyi, and Kim, Jongman. 2011. "A Semi-Preemptive Garbage Collector for Solid State Drives". United States.
@article{osti_1017323,
title = {A Semi-Preemptive Garbage Collector for Solid State Drives},
author = {Lee, Junghee and Kim, Youngjae and Shipman, Galen M and Oral, H Sarp and Wang, Feiyi and Kim, Jongman},
abstractNote = {NAND flash memory is a preferred storage media for various platforms ranging from embedded systems to enterprise-scale systems. Flash devices do not have any mechanical moving parts and provide low-latency access. They also require less power compared to rotating media. Unlike hard disks, flash devices use out-of-update operations and they require a garbage collection (GC) process to reclaim invalid pages to create free blocks. This GC process is a major cause of performance degradation when running concurrently with other I/O operations as internal bandwidth is consumed to reclaim these invalid pages. The invocation of the GC process is generally governed by a low watermark on free blocks and other internal device metrics that different workloads meet at different intervals. This results in I/O performance that is highly dependent on workload characteristics. In this paper, we examine the GC process and propose a semi-preemptive GC scheme that can preempt on-going GC processing and service pending I/O requests in the queue. Moreover, we further enhance flash performance by pipelining internal GC operations and merge them with pending I/O requests whenever possible. Our experimental evaluation of this semi-preemptive GC sheme with realistic workloads demonstrate both improved performance and reduced performance variability. Write-dominant workloads show up to a 66.56% improvement in average response time with a 83.30% reduced variance in response time compared to the non-preemptive GC scheme.},
doi = {},
url = {https://www.osti.gov/biblio/1017323}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Jan 01 00:00:00 EST 2011},
month = {Sat Jan 01 00:00:00 EST 2011}
}

Conference:
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