Blueprint and First Experiences Bridging Hardware Virtualization and Global Grids for Advanced Scientific Computing: Designing and Building a Global Edge Services Framework (ESF) for OSG, EGEE, and LCG

We report on first experiences with building and operating an edge services framework (ESF) based on Xen virtual machines instantiated via the workspace service in Globus toolkit, and developed as a joint project between EGEE, LCG, and OSG. Many computing facilities are architected with their compute and storage clusters behind firewalls. Edge services (ES) are instantiated on a small set of gateways to provide access to these clusters via standard grid interfaces. Experience on EGEE, LCG, and OSG has shown that at least two issues are of critical importance when designing an infrastructure in support of ES. The first concerns ES configuration. It is impractical to assume that each virtual organization (VO) using a facility will employ the same ES configuration, or that different configurations will coexist easily. Even within a VO, it should be possible to run different versions of the same ES simultaneously. The second issue concerns resource allocation: it is essential that an ESF be able to effectively guarantee resource allocation (e.g., memory, CPU, and networking) to different VOs. By providing virtualization on the level of instruction set architecture, virtual machines (VMs) allow configuration of independent software stacks for each VM executing on a resource. Modern implementations of this abstraction are extremely efficient and have outstanding fine-grained enforcement capabilities. To securely deploy VMs, we have extended the design of, and use, workspace service in the Globus toolkit, which allows a VO administrator to dynamically launch appropriately-configured system images. In addition, we are developing a library of such images, reflecting the needs of presently participating communities ATLAS, CMS, and CDF. In this paper, we report on first experiences designing, building and operating this edge services framework.