Thank you for your info, Dennis.
What I want is just an external hard drive system that uses USB 3 as it is faster to read and write than an ethernet cable set up. Ethernet is limited to 1Tbit/sec which is 125MByte/sec whereas USB in a RAID 5 set up will get me at least 170MB/sec speed. The reason I want fast read and write speeds is that my 16bit TIFF files are 205MB which means an ethernet connection takes over 3 seconds to load, whereas USB 3 will be just over a second. The difference doesn't sound much, but when you are processing many files at a time, the time adds up! So, all I want is a simple external hard drive system that has room for 4 x 4TB hard drives that can use RAID 5 for loss security.
This is the type of thing I would like:
http://cplonline.com.au/orico-5-bay-...FdgRvQod2UgISg
However, I am just a bit reticent to get this brand as it is Chinese. I would rather stick to the known brands.