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Tail packing - Wikipedia, the free encyclopedia
Some file systems have since been designed to take advantage of this unused space, and can pack the tails of several files in a single shared tail block. While this may, at first, seem like it would significantly increase file fragmentation, the negative effect can be mitigated with readahead features on modern operating systems – when dealing with short files, several tails may be close enough to each another to be read together, and thus a disk seek is not introduced. Such file systems often employ heuristics in order to determine whether tail packing is worthwhile in a given situation. In some scenarios where the majority of files are shorter than half the block size, tail packing can increase storage efficiency even more than twofold, compared to file systems without tail packing.[1]

This not only translates into conservation of disk space, but may also introduce performance increases, as due to higher locality of reference, less data has to be read, also translating into higher disk cache efficiency. However, these advantages can be negated by the increased complexity of implementation.[2]

As of December 2006, the only notable file systems with support for tail packing are ReiserFS and Reiser4.

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