In order to have enough space on your home server, it is the best to connect a SATA disk. This has the advantage to a USB disk that you can also store the databases reliable to the SATA disk. I always had problems storing them on a USB-Disk. And if you have a hard drive connected, you can install the root file system to the disk, so that the banana boots from disk from now on.
Have a look at the polarity of the power cables of the SATA cable. The black wire should be on the left. Unfortunately I had to cut the cable and reverse them (sorry Frank:-)).