External Storage Device Recommendations
The recommended format for storage devices/volumes that Studiocode files will be saved to is Mac OS Extended Journaled (aka HFS+). This includes servers and external hard drives.
If you intend on working with files that are stored on an external hard drive, it must be a thunderbolt or 9-pin firewire connection. USB is not fast enough of a throughput to suffice for all the potential Studiocode functionality that might be utilized.
If you're using an external hard drive simply to store Studiocode files (e.g. not work from the external hard drive), then USB will suffice. It will just be a slower transfer.
Capturing directly to an external hard drive is not recommended.