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 »
- Authors:
-
- ORNL
- 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}
}