Resync Cloud Storage After OS (Re-)Install

[pseudoware]

~20 GBs of files exist on my D: drive and are synced w/either Dropbox, Skydrive or Google Drive. I am replacing my C: drive and doing a fresh Win7 install (no, I can't restore a system image).

I will eventually re-install the desktop apps for those three cloud services and point them to their respective folders on D: The physical files should still be in sync, but will each service need to go through an indexing or "inventory" process or something? Basically, is it going to take a long time until reaching "synced" or "up to date" status for each? Thanks.

 

[pseudoware]

If helpful to anyone, Dropbox and SkyDrive are intelligent enough to recognize files that have been previously synced. Indexing ~18GBs in DB took about 10 minutes.

Google Drive isn't so smart. It doesn't offer an option to merge existing files. When manually selecting your local GD folder, it would only let me select an empty folder. After choosing an empty folder, I tried moving over folders that were previously synced, but GD would just create a duplicate folder of each from the cloud. Stupid.