Certainly some variation of linux, but there are many of those. For drive pooling, your options are btrfs or zfs. Of those, zfs is the most mature and capable - the only drawback is that once you make a pool you can't easily change the number of drives in it. A small limitation.
Drive pooling as ZFS does it is a replacement for RAID. You generally don't need RAID these days, except for fault-tolerant boot drives in high-availability servers.
Ignore the ZFS "1GB per TB" thing. It's old advice. Use, ZFS does like lots-o-ram because of the way it uses caching. But it doesn't need that much. Your 16GB plan is plenty. You could probably do it in 8GB.