Caching technologies for Tier-2 sites: A UK perspective

¹ University of Glasgow, Glasgow, G12 8QQ UK
² Rutherford Appleton Laboratory, Harwell Campus, Oxon, OX11 0QX, UK
³ The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
⁴ Queen Mary University of London, Mile End Rd, E1 4NS, UK
⁵ University of Edinburgh, King’s Buildings, Edinburgh, EH9 3FD, UK
⁶ Durham University, Stockton Road, Durham, DH1 3LE, UK

Published online: 17 September 2019

Abstract

Pressures from both WLCG VOs and externalities have led to a desire to "simplify" data access and handling for Tier-2 resources across the Grid. This has mostly been imagined in terms of reducing book-keeping for VOs, and total replicas needed across sites. One common direction of motion is to increasing the amount of remote-access to data for jobs, which is also seen as enabling the development of administratively-cheaper Tier-2 subcat-egories, reducing manpower and equipment costs. Caching technologies are often seen as a "cheap" way to ameliorate the increased latency (and decreased bandwidth) introduced by ubiquitous remote-access approaches, but the usefulness of caches is strongly dependant on the reuse of the data thus cached. We report on work done in the UK at four GridPP Tier-2 sites - ECDF, Glasgow, RALPP and Durham - to investigate the suitability of transparent caching via the recently-rebranded XCache (Xrootd Proxy Cache) for both ATLAS and CMS workloads, and to support workloads by other caching approaches (such as the ARC CE Cache).