  This paper introduces the Wave Transactional Filesystem (WTF), a novel,
transactional, POSIX-compatible filesystem based on a new file slicing API that
enables efficient file transformations. WTF provides transactional access to a
distributed filesystem, eliminating the possibility of inconsistencies across
multiple files. Further, the file slicing API enables applications to construct
files from the contents of other files without having to rewrite or relocate
data. Combined, these enable a new class of high-performance applications.
Experiments show that WTF can qualitatively outperform the industry-standard
HDFS distributed filesystem, up to a factor of four in a sorting benchmark, by
reducing I/O costs. Microbenchmarks indicate that the new features of WTF
impose only a modest overhead on top of the POSIX-compatible API.
