Modern file systems maintain extensive metadata about stored files. While metadata typically is useful, there are situations when the additional overhead of such a design becomes a problem in terms of performance. This is especially true for parallel and cluster file systems, where every metadata operation is even more expensive due to their architecture. In this paper several changes made to the parallel cluster file system Parallel Virtual File System (PVFS) are presented. The changes target at the optimization of workloads with large numbers of small files. To improve the metadata performance, PVFS was modified such that unnecessary metadata is not managed anymore. Several tests with a large quantity of files were performed to measure the benefits of these changes. The tests have shown that common file system operations can be sped up by a factor of two even with relatively few changes.

@article{DFSSTEMOIP09,
	author	 = {Michael Kuhn and Julian Kunkel and Thomas Ludwig},
	title	 = {{Dynamic file system semantics to enable metadata optimizations in PVFS}},
	year	 = {2009},
	publisher	 = {John Wiley and Sons Ltd.},
	address	 = {Chichester, UK},
	journal	 = {Concurrency and Computation: Practice and Experience},
	series	 = {21-14},
	pages	 = {1775--1788},
	issn	 = {1532-0626},
	doi	 = {http://dx.doi.org/10.1002/cpe.1439},
	abstract	 = {Modern file systems maintain extensive metadata about stored files. While metadata typically is useful, there are situations when the additional overhead of such a design becomes a problem in terms of performance. This is especially true for parallel and cluster file systems, where every metadata operation is even more expensive due to their architecture. In this paper several changes made to the parallel cluster file system Parallel Virtual File System (PVFS) are presented. The changes target at the optimization of workloads with large numbers of small files. To improve the metadata performance, PVFS was modified such that unnecessary metadata is not managed anymore. Several tests with a large quantity of files were performed to measure the benefits of these changes. The tests have shown that common file system operations can be sped up by a factor of two even with relatively few changes.},
	url	 = {http://onlinelibrary.wiley.com/doi/10.1002/cpe.1439/pdf},
}