한국해양대학교

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A Study on Data Placement Policy for Storage Systems considering File System Input/Output Characteristics

DC Field Value Language
dc.contributor.advisor 백승재 -
dc.contributor.author 구성민 -
dc.date.accessioned 2024-01-03T16:09:38Z -
dc.date.available 2024-01-03T16:09:39Z -
dc.date.created 2022-09-06 -
dc.date.issued 2022 -
dc.identifier.uri http://repository.kmou.ac.kr/handle/2014.oak/13014 -
dc.identifier.uri http://kmou.dcollection.net/common/orgView/200000642629 -
dc.description.abstract In a computer system with a hierarchical structure, storage is the main bottleneck of the system’s performance. Therefore, an efficient data management policy can improve the performance. Intrinsically, data are categorized into hot and cold according to their access frequency. Various studies have been conducted to efficiently manage hot data for better performance. However, previous studies incur runtime computational and memory overhead and performance degradation due to faulty classification. In this paper, we propose a novel data placement scheme for storage systems considering file system I/O characteristics. In the file system’s perspective, meta and journal data are hot data as they are more frequently accessed than user data. Semantic structures of a file system lead to unique disk I/O patterns. Using file system’s semantic information, the proposed scheme discerns hot data, including meta and journal data. Then, hot data are placed into the same block in SSDs to reduce garbage collection overhead and into the middle of the track in hard disk drives to reduce seek time. As the hot data classification is inferred from the immovable file system structure, the proposed scheme is free from faulty classification. The proposed scheme is implemented in QEMU with an SSD simulator called FEMU, and demonstrated by three benchmarks, namely Postmark, YCSB, and Filebench. The results showed that our scheme improved the storage system performance up to 173.81% with an average of 47.62% in EXT4 and up to 19.79% with an average of 7.27% in XFS. Also, the results showed that the scheme mitigated Write Amplification Factor for a longer lifetime of SSDs. In detail, erase operations were decreased up to 22.31% with an average of 10.36% in EXT4, and up to 4.58% with an average of 2.5% in XFS. The number of valid data copy in a victim block decreased up to 73.07% with an average of 29.62% in EXT4 and up to 49% with an average of 13.45% in XFS. The contribution of this paper is as follows. First, we demonstrated that each file system had a unique I/O pattern and meta and journal data were more frequently accessed than user data. Second, for a better performance and lifetime of the SSDs, we proposed a data placement policy that exploited semantic information of a file system. Third, we showed that the policy incurred negligible runtime overhead, therefore, it could be executed inside the SSDs without host-side support. -
dc.description.tableofcontents Chapter 1. Introduction 1 Chapter 2. Background 7 2.1 HDD (Hard Disk Drive) 7 2.2 Flash Memory 9 2.3 FTL (Flash Translation Layer) 13 2.4 Allocation Policy 20 2.5 File System 26 2.5.1 exFAT 28 2.5.2 EXT4 32 2.5.3 XFS 36 Chapter 3. Uniqueness of I/O Pattern of File Systems 39 Chapter 4. Design 52 4.1 Placement Policy for SSD 52 4.2 Placement Policy for HDD 54 Chapter 5. Implementation 55 5.1 Determine File System 57 5.2 Calculate Hot Area 58 5.3 Data Placement Policy 66 Chapter 6. Evaluation 69 6.1 Performance Results 69 6.2 Results of Hybrid SSD 76 Chapter 7. Conclusion 77 REFERENCES 79 -
dc.format.extent 93 -
dc.language eng -
dc.publisher 한국해양대학교 해양과학기술전문대학원 -
dc.rights 한국해양대학교 논문은 저작권에 의해 보호받습니다. -
dc.title A Study on Data Placement Policy for Storage Systems considering File System Input/Output Characteristics -
dc.type Dissertation -
dc.date.awarded 2022-08 -
dc.embargo.terms 2022-09-06 -
dc.contributor.department 해양과학기술전문대학원 해양과학기술융합학과 -
dc.contributor.affiliation 한국해양대학교 해양과학기술전문대학원 해양과학기술융합학과 -
dc.description.degree Doctor -
dc.identifier.bibliographicCitation 구성민. (2022). A Study on Data Placement Policy for Storage Systems considering File System Input/Output Characteristics. -
dc.contributor.specialty 컴퓨터공학 -
dc.identifier.holdings 000000001979▲200000002983▲200000642629▲ -
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