I have an unRAID system with about 6TB of space (1 x 2TB + 3 x 1.5TB + 1 x 2TB parity). I run the 5 disks and haven't bothered with a cache drive. I get about 15-20MByte/sec write speed and read speeds peaking around 35-40MByte/sec

There is some user level security - you can create user shares rather than just one access for all

The file system that does the merge I don't think is using mhddfs. The mount shows as just


I use it as a Crashplan destination to backup machines around the house and also backup its major stores to the Crashplan online backup system.

I run it in a HP N36L NAS enclosure I got fairly cheap. It's low power but not super low power as the drives don't get to spin down much (but unRAID does support that). I get about 75W normal load. I also run two VMs. One is a torrent downloader and the other is my firewall running ClearOS. I have VirtualBox providing the virtualisation.

It does have a level of control of which files go where. You can assign shares to particular drives or exclude particular drives. You can also set it up to not split across drives below a certain depth.

Any questions - ask away.