Confused about a usb cable?

Would it hurt my external hard drive or data if I only used 1 port of a usb y-cable?

• I have a 500gb Ultra-Speed external hard drive which came with just one usb y-cable connector. When I first got it, I didn't realize that I had to plug-in both ends of the y-cable in the computer (I only plugged in one and left the extra one hanging). I already transferred almost 500gb at that one time. Now that I returned to it, I wonder and ask: By only using 1 usb port of the y-cable, would it harm or do anything to the external hard drive or my transferred files on it? I also should note that there was no "warning/problem" messages when or after doing this and the 450+gb transfer was successful (the folder with all the contents was there and the "copying" box was gone after it finished). I guess I worry to much but it is good to know this. I looked at and tested some of the files and they seem to be perfectly fine. I also been looking all over the internet for someone who also asked this same question but I found nothing so I thought I might as well be the first one to ask this question. My external hard drive is also a "Ultra-Speed" if that helps. I think maybe the y-cable was for the ultra speed transfer but now I'm learning that one end supplies power and the other end transfers the data, but since my experience was successful I am confused... Thank you for your time and help in advance!

• Answer:

  The y cable is so it gets enough power, one is data and the other is to take another power feed for the drive, if you managed to actually transfer data with just one end then well done most wont even start up. But once the transfer is done you are fine, the data cant break if it confirmed it is on the disc, you might want to connect it properly and scan it with check disk or other disk utility to be sure but other than that it shouldnt be a problem