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by Jason Snell & Dan Moren

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By Jason Snell

StrongSync: A peek at the future of cloud files on the Mac

Note: This story has not been updated since 2021.

This is Google Drive, but it looks just like iCloud Drive.

Long-time Mac storage utility maker ExpanDrive has launched StrongSync, a $50 utility that… sort of does what ExpanDrive already does? Like its big brother, StrongSync allows you to view cloud storage services as if they were hard drives mounted on your Mac.

StrongSync currently just works with Box, OneDrive for Business, Google Drive, and Sharepoint, with other services on the way. But it’s perhaps most interesting as a sign of how Apple sees the future of cloud storage on the Mac.

Right now, cloud storage providers such as those services I mentioned above, and others such as Dropbox, work on the Mac via kernel extensions, a method of modifying the Mac system software that is not going to stick around much longer because of Apple’s increased focus on macOS security.

For storage providers the alternative to using kernel extensions is macOS Big Sur’s File Provider framework. This framework basically allows third-party apps to provide a bridge between the Mac’s filesystem and their cloud-storage providers of choice. ExpanDrive says that StrongSync is the first macOS File Provider app to ship.

Once you log in to a cloud service via StrongSync, you get a view into that service that’s very much like the view you get when you look at iCloud Drive. That’s because Apple is taking the work it did to supporting its own cloud-storage system, including support for on-demand files right within the APFS filesystem, and allowing other apps to tie into it.

In Finder, files in the cloud have little gray cloud icons with arrows pointing down to indicate they’ll need to be downloaded before they can be accessed. Opening a file in an app will kick off a download, and then the file will open once the download is complete. Files are updated as you use them, and you can right-click on a file and choose Remove Download to delete the local version of the file. Apple also has the ability to automatically wipe out any locally stored file if space is getting low, knowing that there’s a synced version of it in the cloud.

This is clearly where things are going, but today it’s still a bit rough. When StrongSync worked with my Google Drive, it was great. But sometimes a file download would get stuck, and then nothing would happen until I quit and re-launched StrongSync. (To be fair, this is better than when an iCloud Drive download gets stuck and I have no recourse at all!)

The writing is on the wall for existing cloud-storage systems, and I’d expect that most of them will adopt the File Provider framework over the next year or so. Assuming that File Provider is robust and stable—a big assumption, given the frustrations I’ve had with iCloud Drive—it has the potential to be the way we interact with Dropbox, Google Drive, OneDrive, and other providers on our Macs.

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