论文标题

从对象存储节点IO堆栈的引擎盖分析下的学习

Learnings from an Under the Hood Analysis of an Object Storage Node IO Stack

论文作者

Mishra, Pratik, Pitchumani, Rekha, Kee, Yang Suk

论文摘要

传统的对象商店建立在传统的OS存储堆栈之上,I/O请求通常通过多个繁重和冗余层转移。物体管理的复杂性随着存储子系统的性能,一致性和容忍性的耐受性的不断增长而急剧增长。简而言之,在I/O数据路径中遇到了更多的中间层,每个传递层都添加了自己的语法和语义。从而增加请求处理的开销。在本文中,通过对对象存储节点的综合分析分析,我们表征了对象存储(和用户应用)工作负载对OS I/O堆栈的影响及其随后对基础对象存储设备(OSD)的波纹效果。我们观察到,基于OS的I/O存储堆栈的旧架构以及复杂的数据管理策略会导致末端存储设备能够交付的功能与在生产环境中实际提供的功能之间的性能不匹配。因此,从开发更快的存储设备中获得的收益通常被无效。这些问题在高度并发和多重云环境中变得更加明显。由于对象管理的相关问题以及OS I/O软件堆栈的漏洞,我们讨论了一种新的存储设备(称为对象驱动器)的潜力。三星钥匙值SSD(KV-SSD)[1]和Seagate动力学驱动器[2]是对象驱动器的经典工业实现,可以将主机数据管理功能卸载到存储设备。这导致了整个存储堆栈的简化。基于我们的分析,我们认为对象驱动器可以减轻数据管理高度征收的征收的对象商店,而传统操作系统(OS)堆栈的时间储备为20-38%。

Conventional object-stores are built on top of traditional OS storage stack, where I/O requests typically transfers through multiple hefty and redundant layers. The complexity of object management has grown dramatically with the ever increasing requirements of performance, consistency and fault-tolerance from storage subsystems. Simply stated, more number of intermediate layers are encountered in the I/O data path, with each passing layer adding its own syntax and semantics. Thereby increasing the overheads of request processing. In this paper, through comprehensive under-the-hood analysis of an object-storage node, we characterize the impact of object-store (and user-application) workloads on the OS I/O stack and its subsequent rippling effect on the underlying object-storage devices (OSD). We observe that the legacy architecture of the OS based I/O storage stack coupled with complex data management policies leads to a performance mismatch between what an end-storage device is capable of delivering and what it actually delivers in a production environment. Therefore, the gains derived from developing faster storage devices is often nullified. These issues get more pronounced in highly concurrent and multiplexed cloud environments. Owing to the associated issues of object-management and the vulnerabilities of the OS I/O software stacks, we discuss the potential of a new class of storage devices, known as Object-Drives. Samsung Key-Value SSD (KV-SSD) [1] and Seagate Kinetic Drive [2] are classic industrial implementations of object-drives, where host data management functionalities can be offloaded to the storage device. This leads towards the simplification of the over-all storage stack. Based on our analysis, we believe object-drives can alleviate object-stores from highly taxing overheads of data management with 20-38% time-savings over traditional Operating Systems (OS) stack.

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