Not a tool per se, but the file system supports compression of entire volumes with lzo or zlib. There's been proposed others, and some is already in the works ( https://btrfs.wiki.kernel.org/index.php/Compression ).
It is also a part of the Linux kernel.
Ranked in these QuestionsQuestion Ranking
Pro Good compression
While LZO is by far not the most effective compression algorithm, running it on a per-volume basis allows larger volumes to be shrinked quite well, which in some cases may also increase I/O throughput.
Pro Easy to manage
Just one userspace tool, with which one can manage the entire filesystem, volumes, and subvolumes, create snapshots, change quotas, and more.