The size of the disk segment is also a substantial factor on the performance of both WOLF and LFS. If the size of the disk segment is too large, it would be a little difficult to find enough active data to fill one segment and enough inactive data for another segment. The result will be active data and inactive data are mixed together in a large segment, resulting in poor garbage collection performance. The limited disk bandwidth will also have a negative impact on the overall write cost when the segment buffer size exceeds a threshold. On the contrary, if the segment size is too small, the original benefit of LFS, namely taking the advantage of large disk transfer, is lost.
Figure 6 shows the simulation results with the overall write cost versus the sizes of segment buffers. We can see that for both WOLF and LFS, a segment between 256-1024 KB is good for these kind of workloads.