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By Jason Snell

Syncing feeling: iCloud Drive in macOS Sierra

Note: This story has not been updated for several years.

Documents and Desktop, nestled into iCloud.

So many of macOS Sierra’s new features are about freeing up space from our fast-but-tiny solid-state drives. In addition, Apple has extended support for iCloud Drive to optionally include your Desktop and Documents folder, and mixed those two approaches together to create a third feature, called Optimize Mac Storage.

I like what Apple’s going for, but both of these features have problems, and some of them bit me when I was writing my review of Sierra. Let’s take a much closer look at what’s going on with syncing and optimizing, including the bugs, the missed opportunities, and the workarounds.

Syncing Documents and Desktop to iCloud Drive

In Sierra, iCloud Drive finally gets to break out of its own protected folder and into the system at large.

In reality, that’s not quite what’s going on—when you first install Sierra, you’re asked if you want to sync your Desktop and Documents folders with iCloud. If you turn this feature on, your Desktop and Documents folders are really moved inside iCloud Drive, with the old locations linked to your home folder so that everything behaves more or less normally. (Except when there are bugs—a few of my apps seemed to get confused when those folders changed locations.)

iCloud syncing is pretty robust, and once I got up and running with this feature, it worked as advertised. However, the act of turning it on can be terrifying, especially if you’ve already turned it on while using a different Mac. If your Mac discovers that another Mac is already syncing its Desktop to your iCloud Drive, Sierra will create new folder called “Desktop – Your System Name” inside the Desktop folder within iCloud, and move your files inside. (The same thing happens with your Documents folder.)

What this looks like in the Finder: All your files disappear off of your desktop. Maybe a few new files from your other Mac appear. If you keep your key files on your Desktop, it can be terrifying. However, if you look around, you’ll probably see that “Desktop – Your System Name” folder, and all your files should be in there.

Apparently Apple didn’t anticipate this moment of terror, though it should’ve seen it coming. The right thing to do is probably to generate a warning for users, and maybe leave that folder open in a Finder window. Even better would be to give the user a few options when they turn on Desktop and Documents syncing on a different Mac—keep the two Desktops separate, merge them together, or set either one of the Macs as the “real desktop.” But right now, the first Mac wins and the next Mac stuffs its files into a subfolder and waits for the user to sort it out.

Because I wrote a book about Photos, I bought a huge amount of iCloud space to sync my entire Photos library. As a result, I was able to sync everything in my Desktop folder—even huge audio files—to iCloud without difficulty. If you don’t have enough free iCloud space to sync your Desktop and Documents folders, Apple will offer you the exciting opportunity to buy more. If you decline, Apple won’t let you enable this feature.

(Later, if your folders surpass the amount of space available on iCloud, you’ll get an alert and your files will stop syncing with iCloud. They’ll still be present on your Mac, safe and sound, but syncing will stop until you free up or purchase more iCloud space.)

The trouble with optimizing iCloud storage

Combine the concept of purgeable space and the ability to sync more files with iCloud and you get a third key feature of macOS Sierra. When you turn on syncing of the Desktop and Document folders, the Optimize Mac Storage feature is turned on. (You can turn it off in the iCloud Drive section of the iCloud Preference Pane, and probably should, for now.)

Optimize Mac Storage is a feature that defines files that have been uploaded to iCloud as purgeable, more or less. Apple prioritizes your files so that things you’ve accessed recently will be kept around, but items you haven’t accessed for a long time can be removed. When a file is removed, it’s gone from your hard drive, but it lives on in the cloud, and can be downloaded again by clicking an icon in the Finder or when it’s demanded by an application.

Scary, right? But again, if everything’s working perfectly, you’ve just granted that tiny SSD on your MacBook an extra few hundreds of gigabytes of storage, because it can offload your old junk to the cloud. And if it turns out you need it, you can get it back.

If everything’s working perfectly. And if the system can truly differentiate between files you need and files you don’t.

So something bad happened when I was working on my review of macOS Sierra. As a responsible reviewer, I need to use all the features of a new operating system. That comes with some risks, but that’s why I’m here. Risk (of losing data) is our business.

Here’s what happened: While I was working on a podcast-editing project in Logic Pro X, a bunch of my audio files were removed by Optimize Mac Storage. I keep all my key files and projects on the Desktop, as many people do, and since this is a feature that’s designed to keep your work in sync, I decided I was not going change my workflow one bit.

Apple has since told me that I absolutely ran into several different bugs, as well as a few quirks of the file-management process. Many apps store all of their asset files in a single package file—it’s really a folder, but all the important files are stuffed inside so that if you move the package, everything comes along for the ride. A Keynote presentation file is actually a package with a Keynote document and all of the images and movies you dragged in, all bundled together.

Optimize Mac Storage works great with packages. It’s not going to delve down inside a package and get rid of your files—old projects can be optimized away, but new products will remain on your drive, and nothing gets plucked out of the inside of projects.

The problem with some apps—and Apple’s Logic Pro X and Final Cut Pro X fit into this category—is that either they don’t use packages, or stuffing all your files inside a package is optional. My podcast template keeps audio files in the same folder as my Logic project files, but they don’t live inside a package.

Now, it turns out that App developers can take advantage of file-coordination APIs to designate all the files that a given project is using, even if they’re not inside a package. If Logic Pro X used those APIs, perhaps my files wouldn’t have been touched, because iCloud would recognize that they were part of an active project. Alas, not even Apple’s own apps support all of Apple’s APIs. (Optimize Mac Storage apparently looks at the last time you opened a file in the Finder as a way to help determine the age of a file, but if you open a project file and that file then reads from other files, the feature doesn’t consider them actively used.)

The setup of my project folders, Logic’s lack of support for file coordination, and the bugs that made my Mac think it was much more space constrained than it actually was—this was the situation that conspired to make Optimize Mac Storage look at a few 14-day-old 600MB audio files and decide that they were old junk.

Pro tip: Turn it off or move key files elsewhere

With any luck, Apple’s hot on the case of fixing the bugs. Perhaps the teams in charge of Apple’s pro apps are working on coordinating project files a bit more aggressively. And I suspect that I might be a little responsible for this new Apple tech note, which suggests that if you’re using a pro app, you should move your projects out of synced folders or turn off Optimize Mac Storage.

Yep, that’s Apple saying that people who use pro apps should just turn off or avoid using a major new feature of macOS Sierra. It burns a little—what’s the point of making new productivity features if some classes of Mac user just shouldn’t use them? What’s worse, it points out the larger risk in turning on Optimize Mac Storage: If you keep key files outside of a package—images you’re planning on dropping into a Keynote presentation, for example, but haven’t yet—you risk them being deleted by Optimize Mac Storage.

If your internet connection is permanent, fast and unmetered, this is no big deal. If you’re working on an airplane and discover that one of your files you were counting on is gone, welp… that sucks for you. Optimize Mac Storage offers no user interface, so there’s no way to designate certain files or folders as un-purgeable. It’s all or nothing. Either you take your chances or you walk away.

For many classes of Mac user, the risks are low and the benefits are great. For other classes, the right answer is to do what Apple recommends in its tech note: walk away.

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