dcp (distributed copy)
WARNING: dcp is NOT production quality. It WILL randomly delete files and hurt small adorable animals (really cute ones!). Please only execute it on systems that you don't care about or you'll regret it!
The purpose of dcp is to perform a large number of file copy operations (such as a directory tree with billions of files) across many different nodes in a cluster. Using a filesystem that benefits from heavy parallel reads and writes is recommended.