The Large-File Exception
Explore how Fast File System optimizes storage of large files by distributing data across multiple block groups to maintain access locality. Understand the trade-offs of spreading file blocks, the concept of amortization in disk transfers, and how chunk sizes affect seek and transfer times. This lesson helps you grasp the rationale and mechanics behind the large-file exception policy in FFS and its impact on performance.
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Why are large files an issue?
In FFS, there is one important exception to the general policy of file placement, and it arises for large files. Without a different rule, a large file would entirely fill the block group it is first placed within (and maybe others). Filling a block group in this manner is undesirable, as it prevents subsequent “related” files from being placed within this block group, and thus may hurt file-access locality.
Handling large files
Thus, for large files, FFS ...