Stock the PcDuino3 Nano comes with some flavour of Linux that boots off of some internal NAND which works but is really, really slow. The software installed there when I got mine (early 2015) had a problem with the network driver resulting in very, VERY poor connectivity when attached to gigabit ethernet so be weary of this. At the time I didn't know about this so I 'solved' it by doing everything from within a screen session which I could reconnect to if my network connection got dropped.

If you look at the harddrives being detected in the system log after boot, you'll probably find that only 1 shows up. This is because of the way the SATA port on the board works - it cannot detect if it should operate as being directly connected or using a port multiplier, so it defaults to directly connected meaning it sees the first drive reported by the port multiplier. Don't worry about it, we'll fix that.

I've detailed, in pretty thorough detail, how to install Gentoo Linux onto the MicroSD card here. If you want a different flavour of Linux, that's also fine. Get one for ARMv7 with a hard fp. A good alternative to Gentoo is Arch Linux which officially supports this board.

Note that if you run the 3.4 version of the kernel, which the instructions I linked above will result in, you need to make a small change to one of the driver files to make it initialize the SATA part of the chip such that it works with a port multiplier. At the time I used the 3.4.104 kernel where the change was to drivers/ata/sw_ahci_platform.c line 252. Stock it reads "| AHCI_HFLAG_NO_PMP | AHCI_HFLAG_YES_NCQ)," which you need to change to just "| AHCI_HFLAG_YES_NCQ)," then recompile the kernel and it will now detect all drives attached to the port multiplier.

An alternative to doing this is running the Mainline kernel which is something I would recommend wholeheartedly. On github this tree is called sunxi-next and this is amazingly close to stock mainline. One of the benefits you get here is that the module that drives the SATA part of the device has a parameter (enable_pmp=1) via which you can say if you want port multiplier support or not, which is a much nicer way of setting this up.

At this point your file server should be ready for the world, but performance could use a little help so...