Hardware :: External HD Red Activity - Making Access Noises

For the 1st time, I hooked up my seagate 7200 1tb external hard drive that I put in my own enclosure to my i7 2010 macbook pro. It is formatted to FAT 32 for maximum cross platform compatibility without the need for software etc. I plugged it in via a usb hub. The hard drive has been plugged into a PC prior to this. It mounted & was recognized right away, I got an offer to use it with time machine, but I did not want to use it for this, this one is for photos etc. I could see all my content fine, I could not quite figure out how to just move a folder of content from my mac's drive to the external hard drive. So did edit copy & edit pastes & this worked.

I noticed that while the external was plugged into the mac, it was making an access noise that it makes when files are being accessed or moved, but it was doing it the whole time it was tuned on & plugged in. When it was plugged into my PC, it only made the access noise when files were moving or being accessed, but not just being turned on or plugged in. When files are being accessed or when something is being done, a red activity light blinks/is on, & it was on the whole time while plugged into the mac. Apart from that, it seemed to be ok, I could read & write files, was just curious as to why the red activity light & noise is going on the whole time it is plugged in.