The read and write speed of your particular hard drive will dictate how long it takes for a drive to open aka read a file and save (aka write) a file. Many of the external hard drives we have included on this list are pretty fast which is what you need especially if you're transferring large amounts of photo and video data - after all you don't want to have to spend ages waiting just to get your files from one place to another. Generally speaking, a hard drive with a transfer rate of 250-400mbps will take around 3-5 second to transfer a 2GB file.