I tried Amazon S3 -- not sure it that's the same as cloud drive -- and I baled out on it for use as a backup system. Here's why:
My image files have file create date/times as well as modified date/times. I copy them to a second drive using Beyond Compare. When the primary drive datestamp is newer than that of the same file on my backup drive, I do an update. Easy. Beyond Compare is beautiful for this.
However, there Amazon considers the date/time that the file appeared on their server to be the create date/time. As far as I was able to determine, there is no way to override this to use the original file date/time. Thus, my backup system can't work on Amazon S3.