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arXiv 0803.4223cs.DCcs.NI
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分布式第2层中心的统一存储系统

Unified storage systems for distributed Tier-2 centres

Greig A. Cowan, Graeme A. Stewart, Andrew Elwell

摘要:

大型强子对撞机数据采集的开始将预示着粒子物理学数据量和分布式处理的新时代。数百TB的数据量将被运送到二级中心,由LHC实验使用全球LHC计算网格(WLCG)进行分析。在许多国家,二级中心分布在若干机构之间,例如,在英国地理上分布的GridPP的第二层。这为有效利用这些中心的实验提出了许多挑战,因为CPU和存储资源可能会被细分并暴露在比实验理想情况下想要使用的更小的单元中。此外,在各个中心的存储和CPU之间可能会出现无益的不匹配,这使得难以有效利用第2层的资源。解决此问题的一种方法是统一分布式第2层的存储,将中心的聚合存储作为单个系统呈现。这大大简化了VO的数据管理,VO可以跨第2层访问更多数据。但是,这种方法会导致这样的场景:一个站点的批处理系统上的分析作业必须访问另一个站点上托管的数据。我们调查这种情况下使用格拉斯哥和爱丁堡集群,这是ScotGrid分布式第2层的一部分。特别是,我们看看如何减轻与“远程”数据访问相关的问题,并讨论了LAN访问协议穿越中心之间的WAN的安全问题。

英文摘要:

The start of data taking at the Large Hadron Collider will herald a new era in data volumes and distributed processing in particle physics. Data volumes of hundreds of Terabytes will be shipped to Tier-2 centres for analysis by the LHC experiments using the Worldwide LHC Computing Grid (WLCG). In many countries Tier-2 centres are distributed between a number of institutes, e.g., the geographically spread Tier-2s of GridPP in the UK. This presents a number of challenges for experiments to utilise these centres efficaciously, as CPU and storage resources may be sub-divided and exposed in smaller units than the experiment would ideally want to work with. In addition, unhelpful mismatches between storage and CPU at the individual centres may be seen, which make efficient exploitation of a Tier-2's resources difficult. One method of addressing this is to unify the storage across a distributed Tier-2, presenting the centres' aggregated storage as a single system. This greatly simplifies data management for the VO, which then can access a greater amount of data across the Tier-2. However, such an approach will lead to scenarios where analysis jobs on one site's batch system must access data hosted on another site. We investigate this situation using the Glasgow and Edinburgh clusters, which are part of the ScotGrid distributed Tier-2. In particular we look at how to mitigate the problems associated with ``distant'' data access and discuss the security implications of having LAN access protocols traverse the WAN between centres.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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