Experiences with the KOALA co-allocating scheduler in multiclusters

In multicluster systems, and more generally, in grids, jobs may require co-allocation, i.e., the simultaneous allocation of resources such as processors and input files in multiple clusters. While such jobs may have reduced runtimes because they have access to more resources, waiting for processors in multiple clusters and for the input files to become available in the right locations, may introduce inefficiencies. Moreover, as single jobs now have to rely on multiple resource managers, co-allocation introduces reliability problems. In this paper, we present two additions to the original design of our KOALA co-allocating scheduler (different priority levels of jobs and incrementally claiming processors), and we report on our experiences with KOALA in our multicluster testbed while it was unstable.