闪存存储系统的性能优化研究

发布时间：2018-04-06 03:06

本文选题：写缓存　切入点：虚拟内存　出处：《中国科学技术大学》2013年博士论文

【摘要】：闪存存储系统作为一种高性能、低功耗、非易失的存储设备已经被广泛应用于嵌入式系统、桌面系统以及数据中心。然而闪存存储系统普遍存在写性能较差,不可就地更新和寿命较短等问题。这些问题是闪存存储系统广泛应用的主要障碍。因此,设计有效的管理方案以优化闪存存储系统性能,是闪存存储系统的成功应用至关重要。本论文中我们主要针对闪存存储系统在应用中所表现出的以下几个重要特征来优化闪存性能：(1)闪存存储系统读写操作在读写速度上存在较大的不对称性；(2)闪存存储系统的更新操作具有不可就地更新的特征；(3)闪存存储系统的读、写和擦除操作存在操作粒度不对称的特征。本论文将针对闪存存储系统应用于磁盘缓存系统和外部存储系统展开研究。本文的主要工作和创新如下：首先研究闪存作磁盘缓存系统的问题。基于闪存的磁盘缓存系统研究已久,然而目前的闪存磁盘缓存系统很难满足其寿命和性能的要求。尽管有大量工作关注于优化闪存性能和寿命,然而对于高密度、高随机化的应用,这些方法都无法从根本上解决问题。本文考虑闪存作磁盘缓存的特征,提出了一个混合的磁盘缓存系统。我们通过使用新型非易失性存储器和闪存组合构成混合式磁盘缓存,通过减少闪存低效的写操作和擦除操作来优化闪存的写性能和延长闪存寿命。本文中,我们使用的新型非易失性存储器是相变存储器,它是目前最有发展潜质的非易失性存储器之一。其次研究闪存作外部存储器的问题。我们考虑在此类存储系统中通过主机系统来优化闪存存储系统性能。目前,已有部分工作在虚拟内存系统中通过挖掘闪存读写不对称的特征来设计优化方案。然而这些方案都普遍存在不能够有效利用闪存存储系统中写缓存的问题。写缓存是目前闪存存储系统中的一个重要部件。本文首次设计了一个对写缓存感知的虚拟内存管理方案,通过对写缓存管理和虚拟内存管理的联合设计,从而达到性能最大化。与此同时,为了配合虚拟内存中所提出的管理方案,本文还设计了一个新的写缓存管理方案。虽然从主机系统通过设计虚拟内存管理方案可以有效地改善闪存存储系统性能,然而在很多情况下虚拟内存对外部存储器的设计并不可知。在本文最后部分,我们提出了一个统一的写缓存管理方案。通过对目前现有写缓存管理算法的分析,我们发现目前的写缓存管理方案普遍存在对缓存行访问信息不可知的特征。由此我们设计了一个统一写缓存管理模型。根据这个模型,我们提出了统一的写缓存管理方案用于减少闪存存储系统写操作和擦除操作从而优化闪存存储系统性能和寿命。
[Abstract]:Flash memory storage system is a kind of high performance, low power, nonvolatile storage device has been widely used in embedded system, desktop system and data center. However, widespread flash storage system performance is poor, can not be updated in place and short life problems. These problems are the main obstacle to the wide application of flash memory storage systems therefore, to design an effective management scheme to optimize the performance of flash memory storage system is crucial to the successful application of flash memory storage system. In this thesis, we focus on the flash storage system on application to several important features to optimize the performance of the flash memory: (1) flash memory storage system to read and write operations in the read and write asymmetry high speed; (2) the update operation flash memory storage system has features that cannot be updated in place; (3) flash memory storage system to read, write and erase operations are. This paper will focus on the application of flash memory system to disk cache system and external storage system. The main works and innovations in this paper are as follows:
Study on the first flash memory as the disk cache system. Based on the study of the flash disk cache system for a long time, but the flash disk cache system is difficult to meet the requirements of life and performance. Although there are a lot of work focused on the optimization of flash memory performance and life, but for high density, high application of randomization, these methods are not from the fundamental solution to the problem considered in this paper. The characteristics of flash memory as a disk cache, propose a hybrid disk caching system. We use non-volatile memory and flash memory composed of hybrid disk cache, by reducing the write operation and erase operation of flash flash inefficient to optimize write performance and prolong the lifetime of flash memory in this paper. And we use the new nonvolatile memory is memory, it is currently the most development potential of the nonvolatile memory.
Secondly, flash as external memory. We consider to optimize the performance of flash memory storage system in the storage system through the host system. At present, some work in the virtual memory system through the design optimization program features of flash memory reader asymmetric mining. However these schemes exist can effectively use the write cache of flash memory in the storage system. The write cache is one of the important parts in flash storage system at present. This paper first designed a write cache aware virtual memory management scheme, based on the write cache management and virtual memory management design, so as to achieve maximum performance. At the same time, in order to cope with the proposed virtual memory management scheme in this paper, we also design a new write cache management scheme.
Although effective from the host system through the design of virtual memory management scheme can improve the performance of flash memory storage system, however, in many cases, the design of virtual memory external memory is not known. In the last part of this paper, we propose a unified cache management scheme. Through the writing of the existing write cache management algorithm analysis, we we found that the current write cache management scheme are common features of the cache line access information unknown. Thus we designed a unified write cache management model. According to this model, we propose a cache management scheme for unified write flash memory storage system performance and life optimization to reduce the flash memory storage system write and erase operations thereby.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TP333

【共引文献】