

The transfer can be done in a number of ways, from uploading it using Google Drive web interface via a browser, using the Google Drive sync, to using Google Drive API for file transfer - where the upload through the browser is the most viable option in the given scenario. To be in better control of what is happening with your files consider creating several archives on a local machine, compress them, and transfer them over to the Google Drive. While it never happened that a file would be lost, due to a possibility of problems I would recommend a slightly different approach - assuming there is enough extra space on the local drive. I've experienced multiple instances where the synchronization using Google software under Windows or Mac OS X would result in problems.

Google Drive sync is not always 100% reliable.
