WAFL is used on file servers that include an NVRAM cache for writes.
The WAFL designers took advantage of running on a specific architecture to optimize the file system for random I/O, with a stable-storage cache in front.
Ease of use is one of the guiding principles of WAFL.
Its creators also designed it to include a new snapshot functionality that creates multiple read-only copies of the file system at different points in time, as we shall see.