Jun Seok Lee , Hyun Chan Park , Chuck Yoo

The KIPS Transactions:PartA, Vol. 16, No. 2, pp. 101-112, Apr. 2009
10.3745/KIPSTA.2009.16.2.101,   PDF Download:

Abstract

Existing techniques for defragmentation of the file system need intensive disk operation for some periods at specific time such as disk defragmentation program. In this paper, for solving this problem, we design and implement the automatic and continuous defragmentation free system by distributing the disk operation. We propose the Automatic Layout Scoring(ALS) mechanism for measuring defragmentation degree and suggest the Lazy Copy mechanism that copies the defragmented data at idle time for scattering the disk operation. We search the defragmented file by Automatic Layout Scoring mechanism and then find for empty spaces for that searched file. After lazy copy of searched fils to empty space for preventing that file from being lost, the algorithm solves the defragmentation problem by updating the I-node of that file. We implement these algorithms in Linux and evaluate them for small and defragmented file to get the layout scoring. We outperform the Linux EXT2 file system by 2.4%～10.4% in layout scoring evaluation. And the performance of read and write for various file size is better than the EXT2 by 1%～8.5% for write performance and by 1.2%～7.5% for read performance. We suggest this system for solving the problem of defragmentation automatically without disturbing the I/O task and manual management.

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