TWINS: Server Access Coordination in the I/O Forwarding Layer
Résumé
This paper presents a study of I/O scheduling techniques applied to the I/O forwarding layer. In high-performance computing environments, applications
rely on parallel file systems (PFS) to obtain good I/O performance even when handling large amounts of data. To alleviate the concurrency caused by
thousands of nodes accessing a significantly smaller number of PFS servers, intermediate I/O nodes are typically applied between processing nodes
and the file system. Each intermediate node forwards requests from multiple clients to the system, a setup which gives this component the opportunity
to perform optimizations like I/O scheduling. We evaluate scheduling techniques that improve spatiality and request size of the access patterns.
We show they are only partially effective because the access pattern is not the main factor for read performance in the I/O forwarding layer.
A new scheduling algorithm, TWINS, is presented to coordinate the access of intermediate I/O nodes to the data servers.
Our proposal decreases concurrency at the data servers, a factor previously proven to negatively affect performance. The proposed algorithm is able
to improve read performance from shared files by up to 28% over other scheduling algorithms and by up to 50% over not forwarding I/O.
Origine : Fichiers produits par l'(les) auteur(s)
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