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This paper presents an analysis of a performance bottleneck in enterprise file servers using Linux and proposes a modification to this operation system for avoiding the bottleneck. The analysis shows that metadata cache deallocation of current Linux causes large latency in file-request processing when the operational throughput of a file server becomes large. To eliminate the latency caused by metadata cache deallocation, a new method, called "split reclaim," which divides metadata cache deallocation from conventional cache deallocation, is proposed. It is experimentally shown that the split-reclaim method reduces the worst response time by more than 95% and achieves three times higher throughput under a metadata-intensive workload. The split-reclaim method also reduces latency caused by cache deallocation under a general file-server workload by more than 99%. These results indicate that the split-reclaim method can eliminate metadata cache deallocation latency and make possible the use of commodity servers as enterprise file servers.Index Terms-Cache memory, file servers, memory management, scalability.

SUMMARY We propose a method for shared file cache function for cloned files used by virtual machines, called SCC. The file clone function copies the files faster than conventional (read and write) method. Moreover, the function reduces disk spaces. The function is used to deploy virtual machines in virtual desktop infrastructure because of fast copying a lot of virtual machine disk files. SCC uses the file cache of a shared file as a shared cache among cloned files. The cached data on the shared file are returned to application programs on accessing the shared file via cloned files. Therefore, SCC improves the I/O performance of the shared file due to avoiding disk accesses. In this paper, we implement SCC and evaluate the I/O performance. From the evaluation, we have found SCC improves I/O throughput about 38 times in the case of random read and shared cache hit.

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SUMMARY We propose a method of high‐throughput file‐level deduplication for primary file servers, called partial data background prefetch (PDBP). To achieve high throughput of deduplication, the method reduces the number of disk I/Os issued during deduplication process. Before running deduplication process, the proposed method prefetches a part of data of shred files referred by deduplicated files. After that, the method processes the files that are larger than a file‐size threshold defined by administrators. In this paper, we evaluate a deduplication processing time by using a simulation model of PDBP. Consequently, we confirm that the processing time of PDBP is reduced by about 50% compared to a conventional file deduplication method when the threshold is set to 4 KB.