Many people use OneDrive, Dropbox, Google Drive or other cloud storage provider. Those services offer a great way to protect your data in the case of a major disaster with your home or just your computer - either way it protects your data and that is good thing.
We recommend in the User Guide that you always keep those image folders local to your system even though they are sync'd to the cloud. The big reason is that there is too much delay if every image had to be read from the cloud to your local disk, scanned by TTP, and then when metadata is updated, the whole image has to be read, metadata added, and then the image has to be re-sync'd to the cloud again. Very inefficient! And for those who have Internet bandwidth restrictions it is a challenge to manage those when you are busy tagging lots of photos.
A suggestion is to use a local photo folder - disk space is relatively cheap these days - and have TTP point to the local folder. Then use a tool like MS SyncToy (free from Microsoft) to sync that folder to your local OneDrive, Google Drive or Dropbox folder. This allows you to work locally, make lots of changes, and then when done you can sync the photos folders to another local folder - OneDrive for example. Then OneDrive will take over and grab just the changes and send those to the cloud.
We also strongly recommend the newer SSD (solid state drives) for high performance. Typically they give you 5 to 10 times the speed of spinning disk drives - and usually last longer without failures.
Here is an example of the MS SyncToy folder pair for this scenario. The right folder is the local Box.net (cloud storage provider) folder. The left folder is the local folder where the main TTP photo library is stored.