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.