I recently moved 150GB of data from one drive to another. Both drives are being backed up by iDrive in the same backup set, both locally and to iDrive servers. After moving this data I expected iDrive to simply recognize that these files had changed location and update the file locations, but not re-upload the data (as the data itself had *not* changed). Instead iDrive re-uploaded all 150GB of data, which required saturating my cable connection's outgoing bandwidth for days.
This seems like a fundamental missing feature, and one I expect any good backup program to have. I realize there is encryption involved, but if the local client simply generates file hashes, you should be able to easily detect whether a file that shows as "new" is in fact simply a *moved* file that already existed. Then you can just change the folder that the backup set indicates that file belongs to, rather than re-uploading the entire thing. Re-uploading wastes the user's bandwidth, and iDrive's bandwidth *and* storage space. Bad design.
iDrive should have per-user (not global!) deduplication and/or file move detection and handle it more appropriately.