Questions about BBB

I'm doing a electronic project and I think that BeagleBone Black may be the solution.

The specifications are as follows:
-Linux with PHP or C, for remote connection to mySQL server and TCP / IP

sockets for connection to cameras.
-Possibility of digital inputs and outputs and analog inputs, UARTs, PWM,...
-Continuos reading and writing files, up 120kbytes size, at rate of 20Mbits/s on storage medium of at least 32GBytes. A SD card will not work.¿Can I connect an external hard drive to USB 2.0 or other mass storage at 20Mbits/s?

Does anyone has done anything like this?

Should be possible. Hard drive might need external power and USB flash drive is probably too slow for sustained writes.