This release contains a number of performance improvements for the Berkeley DB backend. It also comes with an alternative to file_io, named chunk_io. chunk_io has one big advantage over file_io. Where file_io stores all the data in one big file, chunk_io stores the data as 4~128k chunks. When data is deleted from lessfs with chunk_io, it immediately results in free space for the underlying filesystem. The file_io backend only marks space in the blockdata file as being available to be reused, but does not actually shrink the file. To keep the number of files in a single directory to an acceptable maximum the depth of the directory structure can be specified with the CHUNK_DEPTH directive. By default the data will be hashed into 256 directories which is also the minimal required depth.
The chunk_io backend works well with btrfs and to some extend with reiserfs.