Proceedings of the 4th USENIX Conference on File and Storage Technology (FAST '05). San Francisco, CA. December 13-16, 2005.
Steven W. Schlosser†, Jiri Schindler‡, Stratos Papadomanolakis , Minglong Shao Anastassia Ailamaki, Christos Faloutsos, Gregory R. Ganger
† Intel Research Pittsburgh
‡ EMC Corporation
Carnegie Mellon University
Pittsburgh, PA 15213
With the deeply-ingrained notion that disks can ef
ficiently access only one dimensional data, current approaches
for mapping multidimensional data to disk
blocks either allow efficient accesses in only one dimension,
trading off the efficiency of accesses in other dimensions,
or equally penalize access to all dimensions.
Yet, existing technology and functions readily available
inside disk firmware can identify non-contiguous logical
blocks that preserve spatial locality of multidimensional
datasets. These blocks, which span on the order of a
hundred adjacent tracks, can be accessed with minimal
positioning cost. This paper details these technologies,
analyzes their trends, and shows how they can be exposed
to applications while maintaining existing abstractions.
The described approach can achieve the best possible
access efficiency afforded by the disk technologies:
sequential access along primary dimension and access
with minimal positioning cost for all other dimensions. Experimental evaluation of a prototype implementation demonstrates a reduction of overall I/O time for multidimensional data queries between 30% and 50% when compared to existing approaches.
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