|Thanks for the reply, here is some more information...|
Both drives are external Seagate 500 GB drives.
They were purchased to backup files on my computer's C drive that contained documents and photographs. I believe in triple redundancy.
I started to copy the data from my C drive using a program suggested to me called TeraCopy. However, there were some errors reported (something to do with some file names being too long) and I cancelled this transfer. I then deleted the files that had been copied over with TeraCopy to that point, and started again. This time, I simply used the "Copy Here" feature provided by Windows and no errors appeared.
After comparing the original C drive files to those on the external drive, the size was the same. The number of folders and files was also the same. It all looked good.
I repeated this process to copy the same C drive files to the other external drive. Once again, the size was the same. The number of folders and files was also the same.
So, everything looked good as far as the data copied. It was all there. But then, when I looked at the "free space" left on the drive, it was vastly different.
message edited by Castle_4444