StableBit DrivePool - State of the art, file based drive pooling software.
TrueNAS Core - TrueNAS Core (formerly FreeNAS) is a storage operating system strong and robust enough to meet the needs of enterprise level businesses.
Drive Bender - Drive Bender, class leading storage pooling technology
OpenMediaVault - OpenMediaVault is the next generation network attached storage (NAS) solution based on Debian Linux.
mhddfs - The driver combines a several mount points into the single one.
XigmaNAS - File Sharing, OS & Utilities, and Security & Privacy