Redundant array of inexpensive disk （RAID）10 is known as the most reliable disk array architecture to tolerate up to half of total disk failures, but failure of two disks in the same mirror set still results in data...Redundant array of inexpensive disk （RAID）10 is known as the most reliable disk array architecture to tolerate up to half of total disk failures, but failure of two disks in the same mirror set still results in data loss. In this paper, we propose a new disk array architecture, mirroring and parity protected RAID （MP-RAID）, which combines both mirroring and parity techniques to further improve reliability of disk arrays. The main idea behind MP-RAID is to protect the data by both mirroring and parity techniques： keep two copies of data in the same mirror set and update the parity block in the log disk within the same parity groups. Reliability analysis shows that the reliability of MP-RAID, in terms of mean time to data loss （MTTDL）, is much better than RAID10 and RAID5.展开更多
基于单容错编码的数据布局已经不能满足存储系统对可靠性越来越高的要求,而现有的基于多容错编码的数据布局普遍存在编码解码复杂,计算负载大等缺点。文中设计了一种基于双奇偶校验的双容错数据布局DP-RA ID。该布局只需要在磁盘数量为...基于单容错编码的数据布局已经不能满足存储系统对可靠性越来越高的要求,而现有的基于多容错编码的数据布局普遍存在编码解码复杂,计算负载大等缺点。文中设计了一种基于双奇偶校验的双容错数据布局DP-RA ID。该布局只需要在磁盘数量为素数的RA ID 5阵列系统中增加1个校验磁盘,通过水平和对角方向的双重奇偶校验实现双容错。该布局的双重校验条纹长度相同,结构简单,易于实现。而且该布局的编码解码算法简单,计算负载小。研究表明该布局与RA ID 5相比,写操作性能会有少许的下降,读操作性能不变,而可靠性大幅度提高。展开更多
In recent years,a lot of XOR-based coding schemes have been developed to tolerate double disk failures in Redundant Array of Independent Disks (RAID) architectures,such as EVENODD-code,X-code,B-code and BG-HEDP. Despi...In recent years,a lot of XOR-based coding schemes have been developed to tolerate double disk failures in Redundant Array of Independent Disks (RAID) architectures,such as EVENODD-code,X-code,B-code and BG-HEDP. Despite those researches,the decades-old strategy of Reed-Solomon (RS) code remains the only popular space-optimal Maximum Distance Separable (MDS) code for all but the smallest storage systems. The reason is that all those XOR-based schemes are too difficult to be implemented,it mainly because the coding-circle of those codes vary with the number of disks. By contrast,the coding-circle of RS code is a constant. In order to solve this problem,we develop a new MDS code named Latin code and a cascading scheme based on Latin code. The cascading Latin scheme is a nearly MDS code (with only one or two more parity disks compared with the MDS ones). Nev-ertheless,it keeps the coding-circle of the basic Latin code (i.e. a constant) and the low encod-ing/decoding complexity similar to other parity array codes.展开更多
X-Code is one of the most important redundant array of independent disk （RAID）-6 codes which are capable of tolerating double disk failures. However, the code length of X-Code is restricted to be a prime number, and...X-Code is one of the most important redundant array of independent disk （RAID）-6 codes which are capable of tolerating double disk failures. However, the code length of X-Code is restricted to be a prime number, and such code length restriction of X-Code limits its usage in the real storage systems. Moreover, as a vertical RAID-6 code, X-Code can not be extended easily to an arbitrary code length like horizontal RAID-6 codes. In this paper, a novel and efficient code shortening algorithm for X-Code is proposed to extend X-Code to an arbitrary length. It can be further proved that the code shortening algorithm maintains the maximum-distance-separable （MDS） property of X-Code, and namely, the shortened X-Code is still MDS code with the optimal space efficiency. In the context of the shortening algorithm for X-Code, an in-depth performance analysis on X-Code at consecutive code lengths is conducted, and the impacts of the code shortening algorithm on the performance of X-Code in various performance metrics are revealed.展开更多
固态盘(solid state drive,SSD)因为其优越的性能已被大量部署于当前的存储系统中.但是,由于寿命有限,SSD的可靠性受到广泛的质疑.磁盘阵列(redundant arrays of inexpensive disk,RAID)是一种传统的用来提高可靠性的手段,但并不适用于S...固态盘(solid state drive,SSD)因为其优越的性能已被大量部署于当前的存储系统中.但是,由于寿命有限,SSD的可靠性受到广泛的质疑.磁盘阵列(redundant arrays of inexpensive disk,RAID)是一种传统的用来提高可靠性的手段,但并不适用于SSD.这项工作提出一种基于SSD和磁盘的混合存储系统,构建该系统的主要思想是SSD响应所有I/O请求,从而获得较高的性能;磁盘备份所有数据,从而保证系统的可靠性.但是,磁盘的I/O性能显著低于SSD,构建该系统的问题在于磁盘能否及时地备份SSD上的数据.为了解决这一问题,从两方面提出优化:在延迟方面,采用非易失主存弥补磁盘与SSD的延迟差距;在带宽方面,采用两种措施:1)在单块磁盘内部重组I/O请求,使磁盘尽可能的顺序读写;2)采用多块磁盘备份多块SSD,通过将一块SSD上的写请求分散到多块磁盘上,有效应对单块SSD上出现的突发写请求.通过原型系统实现表明,该混合系统是可行的:磁盘能够为SSD提供实时的数据备份;与其他系统相比,该混合系统取得较高的性价比.展开更多
One way to increase storage density is using a shingled magnetic recording(SMR)disk.We propose a novel use of SMR disks with RAID(redundant array of independent disks)arrays,specifically building upon and compared wit...One way to increase storage density is using a shingled magnetic recording(SMR)disk.We propose a novel use of SMR disks with RAID(redundant array of independent disks)arrays,specifically building upon and compared with a basic RAID 4 arrangement.The proposed scheme(called RAID 4SMR)has the potential to improve the performance of a traditional RAID 4 array with SMR disks.Our evaluation shows that compared with the standard RAID 4,when using update in-place in RAID arrays,RAID 4SMR with garbage collection not just can allow the adoption of SMR disks with a reduced performance penalty,but offers a performance improvement of up to 56%.展开更多
This paper presents a novel method, called TSHOVER, for tolerating up to triple disk failures in RAID/DRAID architectures or others reliable storage systems. TSHOVER is two-dimensional code, which employs horizontal c...This paper presents a novel method, called TSHOVER, for tolerating up to triple disk failures in RAID/DRAID architectures or others reliable storage systems. TSHOVER is two-dimensional code, which employs horizontal code and vertical code at the same time with simple exclusive-OR (XOR) computations. This paper shows the new step ascending concepts used in encoding, and it has the capability of realizing fault tolerance. TSHOVER has better data recovery ability to those disk network storage systems with relatively more dynamic changes in the number of disks. Compared with RS and STAR code, TSHOVER has better encoding performance. When updating a data strip, only 6 XOR operations are needed. Both experimental results and theoretical analyses show that TSHOVER has better performance and higher efficiency than other algorithms.展开更多
基金Project supported by the National Basic Research Program of China (Grant No.2004CB318201)the National High-Technology Research and Development Program of China (Grant No.2008AA01A401)the Changjiang Innovative Group of Ministry of Education of China (Grant No.IRT0725)
文摘Redundant array of inexpensive disk （RAID）10 is known as the most reliable disk array architecture to tolerate up to half of total disk failures, but failure of two disks in the same mirror set still results in data loss. In this paper, we propose a new disk array architecture, mirroring and parity protected RAID （MP-RAID）, which combines both mirroring and parity techniques to further improve reliability of disk arrays. The main idea behind MP-RAID is to protect the data by both mirroring and parity techniques： keep two copies of data in the same mirror set and update the parity block in the log disk within the same parity groups. Reliability analysis shows that the reliability of MP-RAID, in terms of mean time to data loss （MTTDL）, is much better than RAID10 and RAID5.
文摘基于单容错编码的数据布局已经不能满足存储系统对可靠性越来越高的要求,而现有的基于多容错编码的数据布局普遍存在编码解码复杂,计算负载大等缺点。文中设计了一种基于双奇偶校验的双容错数据布局DP-RA ID。该布局只需要在磁盘数量为素数的RA ID 5阵列系统中增加1个校验磁盘,通过水平和对角方向的双重奇偶校验实现双容错。该布局的双重校验条纹长度相同,结构简单,易于实现。而且该布局的编码解码算法简单,计算负载小。研究表明该布局与RA ID 5相比,写操作性能会有少许的下降,读操作性能不变,而可靠性大幅度提高。
基金Supported in part by the National High Technology Re-search and Development Program of China (2008 AA01Z-401)the National Science Foundation of China (No.60903028)+1 种基金Doctoral Fund of Ministry of Education of China (20070055054)Science and Technology De-velopment Plan of Tianjin (08JCYBJC13000)
文摘In recent years,a lot of XOR-based coding schemes have been developed to tolerate double disk failures in Redundant Array of Independent Disks (RAID) architectures,such as EVENODD-code,X-code,B-code and BG-HEDP. Despite those researches,the decades-old strategy of Reed-Solomon (RS) code remains the only popular space-optimal Maximum Distance Separable (MDS) code for all but the smallest storage systems. The reason is that all those XOR-based schemes are too difficult to be implemented,it mainly because the coding-circle of those codes vary with the number of disks. By contrast,the coding-circle of RS code is a constant. In order to solve this problem,we develop a new MDS code named Latin code and a cascading scheme based on Latin code. The cascading Latin scheme is a nearly MDS code (with only one or two more parity disks compared with the MDS ones). Nev-ertheless,it keeps the coding-circle of the basic Latin code (i.e. a constant) and the low encod-ing/decoding complexity similar to other parity array codes.
基金supported by the National Basic Research Program of China (Grant Nos.2011CB302300, 2011CB302301)the National High-Technology Research and Development Program of China (Grant Nos.2009AA01A401,2009AA01A402)+1 种基金the National Natural Science Foundation of China (Grant Nos.60873028, 60933002, 61025008)the Changjiang Innovation Group of Education of China (Grant No.IRT0725)
文摘X-Code is one of the most important redundant array of independent disk （RAID）-6 codes which are capable of tolerating double disk failures. However, the code length of X-Code is restricted to be a prime number, and such code length restriction of X-Code limits its usage in the real storage systems. Moreover, as a vertical RAID-6 code, X-Code can not be extended easily to an arbitrary code length like horizontal RAID-6 codes. In this paper, a novel and efficient code shortening algorithm for X-Code is proposed to extend X-Code to an arbitrary length. It can be further proved that the code shortening algorithm maintains the maximum-distance-separable （MDS） property of X-Code, and namely, the shortened X-Code is still MDS code with the optimal space efficiency. In the context of the shortening algorithm for X-Code, an in-depth performance analysis on X-Code at consecutive code lengths is conducted, and the impacts of the code shortening algorithm on the performance of X-Code in various performance metrics are revealed.
文摘固态盘(solid state drive,SSD)因为其优越的性能已被大量部署于当前的存储系统中.但是,由于寿命有限,SSD的可靠性受到广泛的质疑.磁盘阵列(redundant arrays of inexpensive disk,RAID)是一种传统的用来提高可靠性的手段,但并不适用于SSD.这项工作提出一种基于SSD和磁盘的混合存储系统,构建该系统的主要思想是SSD响应所有I/O请求,从而获得较高的性能;磁盘备份所有数据,从而保证系统的可靠性.但是,磁盘的I/O性能显著低于SSD,构建该系统的问题在于磁盘能否及时地备份SSD上的数据.为了解决这一问题,从两方面提出优化:在延迟方面,采用非易失主存弥补磁盘与SSD的延迟差距;在带宽方面,采用两种措施:1)在单块磁盘内部重组I/O请求,使磁盘尽可能的顺序读写;2)采用多块磁盘备份多块SSD,通过将一块SSD上的写请求分散到多块磁盘上,有效应对单块SSD上出现的突发写请求.通过原型系统实现表明,该混合系统是可行的:磁盘能够为SSD提供实时的数据备份;与其他系统相比,该混合系统取得较高的性价比.
文摘One way to increase storage density is using a shingled magnetic recording(SMR)disk.We propose a novel use of SMR disks with RAID(redundant array of independent disks)arrays,specifically building upon and compared with a basic RAID 4 arrangement.The proposed scheme(called RAID 4SMR)has the potential to improve the performance of a traditional RAID 4 array with SMR disks.Our evaluation shows that compared with the standard RAID 4,when using update in-place in RAID arrays,RAID 4SMR with garbage collection not just can allow the adoption of SMR disks with a reduced performance penalty,but offers a performance improvement of up to 56%.
基金the National Natural Science Foundation of China (No. 60403043)
文摘This paper presents a novel method, called TSHOVER, for tolerating up to triple disk failures in RAID/DRAID architectures or others reliable storage systems. TSHOVER is two-dimensional code, which employs horizontal code and vertical code at the same time with simple exclusive-OR (XOR) computations. This paper shows the new step ascending concepts used in encoding, and it has the capability of realizing fault tolerance. TSHOVER has better data recovery ability to those disk network storage systems with relatively more dynamic changes in the number of disks. Compared with RS and STAR code, TSHOVER has better encoding performance. When updating a data strip, only 6 XOR operations are needed. Both experimental results and theoretical analyses show that TSHOVER has better performance and higher efficiency than other algorithms.
