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Fault-Tolerant Implementation of Erasure Codes for Storage Systems
, M.Sc. Thesis Sharif University of Technology ; Miremadi, Ghasem (Supervisor)
Abstract
The increasing size of valuable data emphasizes the importance of applying reliability in storage systems. One way to protect storage system failures is using erasure codes. The advantages of using erasure codes are their low overheads and high reliability. Soft errors caused by high-energetic particles do not only corrupt data in the SSD-based storage systems, but also in the erasure codes. In this regards, it is important to protect erasure code implementations against soft errors. This thesis proposes a fault-tolerant implementation of erasure codes. The proposed method is based on the structure of each erasure code. This method is analytically evaluated on four erasure codes, i.e....
On endurance of erasure codes in SSD-based storage systems
, Article Computer Architecture and Digital Systems (CADS), 17th CSI International Symposium on ; Article number 6714239 , 2013 , Pages 67-72 ; 9781479905621 ; Miremadi, Gh. (Sayyed Ghassem) ; Asadi, H. (Hossein) ; Sharif Univesity of Technology
Abstract
The wear-out of flash-based Solid-State Drives (SSDs) is a main concern that significantly affects their reliability. One major parameter that accelerates SSD wear-out is the number of write-cycles committed to flash chips. The number of write-cycles in SSD-based disk subsystem is highly dependent on the erasure code implemented in Redundant Array of Independent Disks (RAIDs). In this paper, we investigate the impact of erasure codes and the configuration of storage subsystems (i.e., the number of disks participated in the RAID array and stripe unit size) on the endurance of storage systems. The number of write-cycles is considered as a metric to evaluate the endurance of storage system. We...
Implicit effect of decoding time on fault tolerance in erasure coded cloud storage systems
, Article 20th International Computer Science and Engineering Conference: Smart Ubiquitos Computing and Knowledge, ICSEC 2016, 14 December 2016 through 17 December 2016 ; 2017 ; 9781509044207 (ISBN) ; Miremadi, S. G ; Alinezhad Chamazcoti, S ; Sharif University of Technology
Abstract
International Data Company (IDC) has estimated the total amount of digital data stored in the world will reach 40 thousand Exabytes at the end of 2020. The idea of accessing this volume of data, anywhere at any time by exploiting commodity hardware, led to the introduction of cloud storage. The abounded rate and variety of failures in the equipment used in cloud storage systems, placed fault tolerance, at top of the challenges in these systems. Hadoop Distributed File System (HDFS) has provided cloud with reliable storage via replication. Storage overhead of replication is high and therefore it's going to be replaced with erasure codes. Despite the significant number of researches on...
Fault Tolerance in Cloud Storage Systems Using Erasure Codes
, M.Sc. Thesis Sharif University of Technology ; Miremadi, Ghassem (Supervisor)
Abstract
International Data Company (IDC) has reported, at the end of 2020, the total amount of digital data stored in the entire world will reach 40 thousand Exabytes. The idea of accessing this volume of data, anywhere at any time by exploiting commodity hardware, led into the introduction of cloud storage. The abounded rate and variety of failures in the equipment used in cloud storage systems, placed fault tolerance, at top of the challenges in these systems. HDFS layer in Hadoop has provided cloud with reliable storage. Replication is the conventional method to protect data against failures in HDFS. But the storage overhead is a big deal and therefore designers are tending towards erasure codes....
Reliability Improvement in SSD-based Storage Systems with Endurance Enhancement
, Ph.D. Dissertation Sharif University of Technology ; Miremadi, Ghassem (Supervisor)
Abstract
As a new technology, the use of Solid State Disk (SSD) in storage systems is increasing due to its higher performance and lower power consumption as compared to the traditional Hard Disk Drive (HDD). On the contrary, the SSD technology has two serious shortcomings, i.e., 1) it has a higher Bit Error Rate (BER) as the number of Program/Erase (P/E) cycles increases, and 2) it can endure a specific number of P/E cycles, called the write endurance limitation. To overcome the endurance limitation of SSDs, several solutions have been proposed in previous literature. These solutions can be categorized in two levels: 1) SSD-controller, and 2) RAID–Controller. Moreover, it is necessary to consider...
On endurance of erasure codes in SSD-based storage systems
, Article Proceedings - 17th CSI International Symposium on Computer Architecture and Digital Systems, CADS 2013 ; 2013 , Pages 67-72 ; 9781479905621 (ISBN) ; Miremadi, S. G ; Asadi, H ; Computer Society of Iran; IPM ; Sharif University of Technology
IEEE Computer Society
2013
Abstract
The wear-out of flash-based Solid-State Drives (SSDs) is a main concern that significantly affects their reliability. One major parameter that accelerates SSD wear-out is the number of write-cycles committed to flash chips. The number of write-cycles in SSD-based disk subsystem is highly dependent on the erasure code implemented in Redundant Array of Independent Disks (RAIDs). In this paper, we investigate the impact of erasure codes and the configuration of storage subsystems (i.e., the number of disks participated in the RAID array and stripe unit size) on the endurance of storage systems. The number of write-cycles is considered as a metric to evaluate the endurance of storage system. We...
On designing endurance aware erasure code for SSD-based storage systems
, Article Microprocessors and Microsystems ; Volume 45 , 2016 , Pages 283-296 ; 01419331 (ISSN) ; Miremadi, S. G ; Sharif University of Technology
Elsevier
2016
Abstract
Erasure codes are applied in both HDD and SSD storage systems to improve the reliability. The design of erasure codes for SSD-based systems should be performed with respect to a specific feature of SSDs, i.e., endurance. Endurance is defined as the number of Program/Erase (P/E)-cycles that one SSD can endure for reliable operation. The common metric for comparing the endurance of two systems is the number of P/E-cycles, which is yielded by time-consuming simulations. This paper proposes two new metrics called DPD-factor and GDP-pattern, for comparing the effect of erasure codes on the endurance of systems based on their encoding designs, without simulation. With respect to the endurance,...
Reliability Enhancement of SSD-based Storage Systems Using Erasure Codes
, M.Sc. Thesis Sharif University of Technology ; Miremadi, Ghasem (Supervisor)
Abstract
The use of flash-based Solid State Disks (SSDs) has been increased in the past decades because of their high performance and low power consumption. As SSDs have no moving mechanical parts, they are more reliable than HDDs. SSDs have specific errors, such as read, program, and erase disturbs, data retention, and endurance. It is so common in storage systems to apply an array of disks called Redundant Array of Independent Disks (RAID) together for the aim of reliability and performance. Erasure codes are one of the main methods applied in storage systems for the aim of reliability. Erasure codes increase the reliability of storage systems by protecting them against disk failures and sector...
Evaluating Impact of Erasure Codes on Performance and Endurance of SSD-Based RAID Array
, M.Sc. Thesis Sharif University of Technology ; Asadi, Hossein (Supervisor)
Abstract
Performance and reliability are the major concerns in design of data storage systems. Using Redundant Array of Independent Disks (RAID) can enhance both performance and reliability. A commonly used configuration in RAID arrays is erasure codes to further enhance system reliability. Due to promising advantages of Solid-State Drives (SSDs)such as low power, shock resistance, and high I/O performance, designers have been encouraged to replace Hard Disk Drives (HDDs) by SSDs in RAID arrays. SSDs, however, suffer from limited endurance due to erase-before-write operation.In this thesis, we investigate the effect of stripe unite size and the number of disks of a RAID array on the endurance of SSDs...
Can erasure codes damage reliability in SSD-based storage systems?
, Article IEEE Transactions on Emerging Topics in Computing ; Volume 7, Issue 3 , 2019 , Pages 435-446 ; 21686750 (ISSN) ; Safaei, B ; Miremadi, S. G ; Sharif University of Technology
IEEE Computer Society
2019
Abstract
Erasure codes are applied in storage systems including both Hard Disk Drive (HDD) and Solid State Disk (SSD) to protect arrays of disks against failures. Applying these codes in SSD-based systems incurs additional number of Program/Erase (P/E) cycles on each disk, which may accelerate the wear-out of disks. This means that while erasure codes improve reliability of SSD-based systems, they impose a side-effect that may degrade reliability as the number of P/E cycles increases. This paper investigates the benefit and side-effect of erasure codes on reliability of SSD-based systems. The investigation attempts to find out the parameters which improve/damage reliability. This study has been...
EA-EO: Endurance aware erasure code for SSD-based storage systems
, Article Proceedings of IEEE Pacific Rim International Symposium on Dependable Computing, PRDC ; 3 December , 2014 , Pages 76-85 ; ISSN: 15410110 ; ISBN: 9781479964741 ; Miremadi, S. G ; Sharif University of Technology
Abstract
One of the main issues in Solid State Drive (SSD)-based storage systems is endurance which is directly affected by the number of Program/Erase (P/E) cycles. The increment of P/E cycles increases the bit error rate threatening the reliability of SSDs. Erasure codes are used to leverage the reliability of storage systems but they also affect the number of P/E cycles based on their code pattern. A lower dependency between data and parities in the code pattern may lead to smaller number of P/E cycles providing better endurance. This paper introduces an Endurance Aware EVENODD (EA-EO), which minimizes the dependency between data and parities in the coding pattern. A simulation environment is used...
On endurance and performance of erasure codes in SSD-based storage systems
, Article Microelectronics Reliability ; Volume 55, Issue 11 , 2015 , Pages 2453-2467 ; 00262714 (ISSN) ; Delavari, Z ; Miremadi, S. G ; Asadi, H ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Erasure codes are widely used in data storage systems to protect against disk failures. Employing erasure codes in an array of Solid-State Drives (SSDs) in storage systems necessitates designers to revisit different characteristics in comparison to Hard Disk Drives (HDDs), due to non-mechanical property of SSDs. One of the most important characteristics of SSDs is their limitation on the number of Program/Erase (P/E) cycles. By taking into account the characteristics of SSDs, this paper presents a comprehensive analysis to investigate the effects of three well-known erasure codes on the endurance and performance of SSD-based disk subsystems. The three erasure codes, i.e., Reed-Solomon,...
A modeling framework for reliability of erasure codes in SSD arrays
, Article IEEE Transactions on Computers ; Volume 69, Issue 5 , May , 2020 , Pages 649-665 ; Ahmadian, S ; Asadi, H ; Sharif University of Technology
IEEE Computer Society
2020
Abstract
Emergence of Solid-State Drives (SSDs) have evolved the data storage industry where they are rapidly replacing Hard Disk Drives (HDDs) due to their superiority in performance and power. Meanwhile, SSDs have reliability issues due to bit errors, bad blocks, and bad chips. To help reliability, Redundant Array of Independent Disks (RAID) configurations, originally proposed to increase both performance and reliability of HDDs, are also applied to SSD arrays. However, the conventional reliability models of HDD RAID cannot be intactly applied to SSD arrays, as the nature of failures in SSDs are totally different from HDDs. Previous studies on the reliability of SSD arrays are based on the...
Error control for multimedia communications in wireless sensor networks: A comparative performance analysis
, Article Ad Hoc Networks ; Volume 10, Issue 6 , 2012 , Pages 1028-1042 ; 15708705 (ISSN) ; Rabiee, H. R ; Khansari, M ; Salehi, M ; Sharif University of Technology
Abstract
The emerging multimedia applications of Wireless Sensor Network (WSNs) impose new challenges in design of algorithms and communication protocols for such networks. In the view of these challenges, error control is an important mechanism that enables us to provide robust multimedia communication and maintain Quality of Service (QoS). Despite the existence of some good research works on error control analysis in WSNs, none of them provides a thorough study of error control schemes for multimedia delivery. In this paper, a comprehensive performance evaluation of Automatic Repeat Request (ARQ), Forward Error Correction (FEC), Erasure Coding (EC), link-layer hybrid FEC/ARQ, and cross-layer hybrid...