Performance Insulation and Predictability for Shared Cluster Storage

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This research explores design and implementation strategies for insulating the performance of high-end computing applications sharing a cluster storage system. In particular, such sharing should not cause unexpected inefficiency. While each application may see lower performance, due to only getting a fraction of the total attention of the I/O system, none should see less work accomplished than the fraction it receives. Ideally, no I/O resources should be wasted due to interference between applications, and the I/O performance achieved by a set of applications should be predictable fractions of their non-sharing performance. Unfortunately, neither is true of most storage systems, complicating administration and penalizing those that share storage infrastructures.Accomplishing the desired insulation and predictability requires cache management, disk layout, disk scheduling, and storage-node selection policies that explicitly avoid interference. This research combines and builds on techniques from database systems (e.g., access pattern shaping and query-specific cache management) and storage/file systems (e.g., disk scheduling and storage-node selection). Two specific techniques are: (1) Using prefetching and write-back that is aware of the applications associated with data and requests, efficiency-reducing interleaving can be avoided; (2) Partitioning the cache space based on per-workload benefits, determined by recognizing each workload's access pattern, one application's data cannot get an unbounded footprint in the storage server cache.