针对Flash存储器特殊的硬件特性和编程特性,提出了在其底层驱动和上层应用之间增加一个中间层(Logical Disk Sys-tem,LDS)。LDS屏蔽了Flash的硬件特性,间接实现了擦写平衡。LDS的核心是block映射机制。文中介绍了block映射机制的物理块...针对Flash存储器特殊的硬件特性和编程特性,提出了在其底层驱动和上层应用之间增加一个中间层(Logical Disk Sys-tem,LDS)。LDS屏蔽了Flash的硬件特性,间接实现了擦写平衡。LDS的核心是block映射机制。文中介绍了block映射机制的物理块状态管理、物理块逻辑关系管理、映射关系表管理、垃圾回收机制等关键技术。最后通过一个实例对LDS进行性能分析,验证了该方法在实际应用中的可行性。展开更多
Flash disks are being widely used as an important alternative to conventional magnetic disks, although accessed through the same interface by applications, their distinguished feature, i.e., different read and write c...Flash disks are being widely used as an important alternative to conventional magnetic disks, although accessed through the same interface by applications, their distinguished feature, i.e., different read and write cost makes it necessary to reconsider the design of existing replacement algorithms to leverage their performance potential. We propose an adaptive cost-aware replacement policy based on average hit distance (AHD) to control the movement of buffer pages when hits occur, thus pages that are re-visited within AHD will stay still. Such a mechanism makes our method adaptive to workloads of different access patterns. The experimental results show that our method not only adaptively tunes itself to workloads of different access patterns, but also works well for different kind of flash disks compared with existing methods.展开更多
Compared with traditional solid-state drives(SSDs),open-channel SSDs(OCSSDs)expose their internal physical layout and provide a host-based flash translation layer(FTL)that allows host-side software to control the inte...Compared with traditional solid-state drives(SSDs),open-channel SSDs(OCSSDs)expose their internal physical layout and provide a host-based flash translation layer(FTL)that allows host-side software to control the internal operations such as garbage collection(GC)and input/output(I/O)scheduling.In this paper,we comprehensively survey research works built on OCSSDs in recent years.We show how they leverage the features of OCSSDs to achieve high throughput,low latency,long lifetime,strong performance isolation,and high resource utilization.We categorize these efforts into five groups based on their optimization methods:adaptive interface customizing,rich FTL co-designing,internal parallelism exploiting,rational I/O scheduling,and efficient GC processing.We discuss the strengths and weaknesses of these efforts and find that almost all these efforts face a dilemma between performance effectiveness and management complexity.We hope that this survey can provide fundamental knowledge to researchers who want to enter this field and further inspire new ideas for the development of OCSSDs.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
文摘针对Flash存储器特殊的硬件特性和编程特性,提出了在其底层驱动和上层应用之间增加一个中间层(Logical Disk Sys-tem,LDS)。LDS屏蔽了Flash的硬件特性,间接实现了擦写平衡。LDS的核心是block映射机制。文中介绍了block映射机制的物理块状态管理、物理块逻辑关系管理、映射关系表管理、垃圾回收机制等关键技术。最后通过一个实例对LDS进行性能分析,验证了该方法在实际应用中的可行性。
文摘Flash disks are being widely used as an important alternative to conventional magnetic disks, although accessed through the same interface by applications, their distinguished feature, i.e., different read and write cost makes it necessary to reconsider the design of existing replacement algorithms to leverage their performance potential. We propose an adaptive cost-aware replacement policy based on average hit distance (AHD) to control the movement of buffer pages when hits occur, thus pages that are re-visited within AHD will stay still. Such a mechanism makes our method adaptive to workloads of different access patterns. The experimental results show that our method not only adaptively tunes itself to workloads of different access patterns, but also works well for different kind of flash disks compared with existing methods.
基金Project supported by the National Natural Science Foundation of China(No.62025203)。
文摘Compared with traditional solid-state drives(SSDs),open-channel SSDs(OCSSDs)expose their internal physical layout and provide a host-based flash translation layer(FTL)that allows host-side software to control the internal operations such as garbage collection(GC)and input/output(I/O)scheduling.In this paper,we comprehensively survey research works built on OCSSDs in recent years.We show how they leverage the features of OCSSDs to achieve high throughput,low latency,long lifetime,strong performance isolation,and high resource utilization.We categorize these efforts into five groups based on their optimization methods:adaptive interface customizing,rich FTL co-designing,internal parallelism exploiting,rational I/O scheduling,and efficient GC processing.We discuss the strengths and weaknesses of these efforts and find that almost all these efforts face a dilemma between performance effectiveness and management complexity.We hope that this survey can provide fundamental knowledge to researchers who want to enter this field and further inspire new ideas for the development of OCSSDs.
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.
