随着信息技术的快速发展,数据存储的需求日益增长,人们对硬盘读写性能的要求越来越高.相比于机械硬盘,固态硬盘可靠性高、能耗低,无寻道时间开销,逐渐取代机械硬盘成为主流的存储介质.但固态硬盘访问数据时需要经过转换,对应的闪存转换...随着信息技术的快速发展,数据存储的需求日益增长,人们对硬盘读写性能的要求越来越高.相比于机械硬盘,固态硬盘可靠性高、能耗低,无寻道时间开销,逐渐取代机械硬盘成为主流的存储介质.但固态硬盘访问数据时需要经过转换,对应的闪存转换算法对读写性能影响很大.OpenSSD项目提供了一个可开发SSD固件的平台,基于此平台本文针对其上的闪存转换算法进行研究并优化,分析了影响I/O读写性能的各类因素,设计出一种适合CosmosOpenSSD的缓存管理和闪存管理方法,大幅提高了Cosmos Open SSD的性能.展开更多
主存键值(key-value,KV)数据库具有高效性、易用性和可扩展性。由于主存容量有限,一些数据量较大的应用必须使用磁盘进行数据交换。而固态硬盘(solid state disk,SSD)有高速的随机读特点,使用固态硬盘作为主存KV数据库的虚拟内存会提高...主存键值(key-value,KV)数据库具有高效性、易用性和可扩展性。由于主存容量有限,一些数据量较大的应用必须使用磁盘进行数据交换。而固态硬盘(solid state disk,SSD)有高速的随机读特点,使用固态硬盘作为主存KV数据库的虚拟内存会提高对不在主存中的数据的读性能。但是固态硬盘的随机写性能较差,于是提出了针对固态硬盘的写缓冲区优化算法,将多个随机写转化为一个连续写,并设计了固态硬盘虚拟内存的垃圾回收机制,将多个随机写转化为一个连续读和一个连续写,从而提高主存KV数据库的性能。通过改写源代码,将该虚拟内存管理应用于Redis中,并进行了实验测试,结果表明该虚拟内存管理的性能比原有性能最大提升了40%。展开更多
Solid state disks （SSDs） are becoming one of the mainstream storage devices due to their salient features, such as high read performance and low power consump- tion. In order to obtain high write performance and ext...Solid state disks （SSDs） are becoming one of the mainstream storage devices due to their salient features, such as high read performance and low power consump- tion. In order to obtain high write performance and extend flash lifespan, SSDs leverage an internal DRAM to buffer frequently rewritten data to reduce the number of program operations upon the flash. However, existing buffer manage- ment algorithms demonstrate their blank in leveraging data access features to predict data attributes. In various real-world workloads, most of large sequential write requests are rarely rewritten in near future. Once these write requests occur, many hot data will be evicted from DRAM into flash mem- ory, thus jeopardizing the overall system performance. In order to address this problem, we propose a novel large write data identification scheme, called Prober. This scheme probes large sequential write sequences among the write streams at early stage to prevent them from residing in the buffer. In the meantime, to further release space and reduce waiting time for handling the incoming requests, we temporarily buffer the large data into DRAM when the buffer has free space, and leverage an actively write-back scheme for large sequential write data when the flash array turns into idle state. Experi- mental results demonstrate that our schemes improve hit ratio of write requests by up to 10%, decrease the average response time by up to 42% and reduce the number of erase opera- tions by up to 11%, compared with the state-of-the-art buffer replacement algorithms.展开更多
Flash solid-state drives （SSDs） provide much faster access to data compared with traditional hard disk drives （HDDs）. The current price and performance of SSD suggest it can be adopted as a data buffer between mai...Flash solid-state drives （SSDs） provide much faster access to data compared with traditional hard disk drives （HDDs）. The current price and performance of SSD suggest it can be adopted as a data buffer between main memory and HDD, and buffer management policy in such hybrid systems has attracted more and more interest from research community recently. In this paper, we propose a novel approach to manage the buffer in flash-based hybrid storage systems, named hotness aware hit （HAT）. HAT exploits a page reference queue to record the access history as well as the status of accessed pages, i.e., hot, warm, and cold. Additionally, the page reference queue is further split into hot and warm regions which correspond to the memory and flash in general. The HAT approach updates the page status and deals with the page migration in the memory hierarchy according to the current page status and hit position in the page reference queue. Compared with the existing hybrid storage approaches, the proposed HAT can manage the memory and flash cache layers more effectively. Our empirical evaluation on benchmark traces demonstrates the superiority of the proposed strategy against the state-of-the-art competitors.展开更多
文摘随着信息技术的快速发展,数据存储的需求日益增长,人们对硬盘读写性能的要求越来越高.相比于机械硬盘,固态硬盘可靠性高、能耗低,无寻道时间开销,逐渐取代机械硬盘成为主流的存储介质.但固态硬盘访问数据时需要经过转换,对应的闪存转换算法对读写性能影响很大.OpenSSD项目提供了一个可开发SSD固件的平台,基于此平台本文针对其上的闪存转换算法进行研究并优化,分析了影响I/O读写性能的各类因素,设计出一种适合CosmosOpenSSD的缓存管理和闪存管理方法,大幅提高了Cosmos Open SSD的性能.
文摘主存键值(key-value,KV)数据库具有高效性、易用性和可扩展性。由于主存容量有限,一些数据量较大的应用必须使用磁盘进行数据交换。而固态硬盘(solid state disk,SSD)有高速的随机读特点,使用固态硬盘作为主存KV数据库的虚拟内存会提高对不在主存中的数据的读性能。但是固态硬盘的随机写性能较差,于是提出了针对固态硬盘的写缓冲区优化算法,将多个随机写转化为一个连续写,并设计了固态硬盘虚拟内存的垃圾回收机制,将多个随机写转化为一个连续读和一个连续写,从而提高主存KV数据库的性能。通过改写源代码,将该虚拟内存管理应用于Redis中,并进行了实验测试,结果表明该虚拟内存管理的性能比原有性能最大提升了40%。
文摘Solid state disks （SSDs） are becoming one of the mainstream storage devices due to their salient features, such as high read performance and low power consump- tion. In order to obtain high write performance and extend flash lifespan, SSDs leverage an internal DRAM to buffer frequently rewritten data to reduce the number of program operations upon the flash. However, existing buffer manage- ment algorithms demonstrate their blank in leveraging data access features to predict data attributes. In various real-world workloads, most of large sequential write requests are rarely rewritten in near future. Once these write requests occur, many hot data will be evicted from DRAM into flash mem- ory, thus jeopardizing the overall system performance. In order to address this problem, we propose a novel large write data identification scheme, called Prober. This scheme probes large sequential write sequences among the write streams at early stage to prevent them from residing in the buffer. In the meantime, to further release space and reduce waiting time for handling the incoming requests, we temporarily buffer the large data into DRAM when the buffer has free space, and leverage an actively write-back scheme for large sequential write data when the flash array turns into idle state. Experi- mental results demonstrate that our schemes improve hit ratio of write requests by up to 10%, decrease the average response time by up to 42% and reduce the number of erase opera- tions by up to 11%, compared with the state-of-the-art buffer replacement algorithms.
基金Acknowledgements This research was supported by the Nalional Natural Science Foundation of China （Grant No. 61272155） and Ministry of Industry and Information Technology （2010ZX01042-001-001-04）.
文摘Flash solid-state drives （SSDs） provide much faster access to data compared with traditional hard disk drives （HDDs）. The current price and performance of SSD suggest it can be adopted as a data buffer between main memory and HDD, and buffer management policy in such hybrid systems has attracted more and more interest from research community recently. In this paper, we propose a novel approach to manage the buffer in flash-based hybrid storage systems, named hotness aware hit （HAT）. HAT exploits a page reference queue to record the access history as well as the status of accessed pages, i.e., hot, warm, and cold. Additionally, the page reference queue is further split into hot and warm regions which correspond to the memory and flash in general. The HAT approach updates the page status and deals with the page migration in the memory hierarchy according to the current page status and hit position in the page reference queue. Compared with the existing hybrid storage approaches, the proposed HAT can manage the memory and flash cache layers more effectively. Our empirical evaluation on benchmark traces demonstrates the superiority of the proposed strategy against the state-of-the-art competitors.
