StableBit DrivePool - State of the art, file based drive pooling software.
DietPi - Dietpi is a debian based operative system made to install new apps easyer.
btrfs - Btrfs is a modern copy on write (CoW) filesystem for Linux aimed at implementing advanced features...
TinyCore - Simple operating system based on Linux that uses "modules", and loads everything into RAM. Can be persistent too.
Drive Bender - Drive Bender, class leading storage pooling technology
DebianDog - DebianDog is very small Debian Live CD shaped to look and act like Puppy Linux.