Cloud Storage

One of the oldest, most common, and most useful types of cloud service is based on the simple notion of storing your files in the Cloud (instead of, or in addition to, storing them on a hard disk, SSD, or other local storage device).

In fact, many popular cloud storage services try to mimic the operation of a disk plugged into your computer—there’s an icon on your Desktop that you can use just like any other disk (open files, delete files, create subfolders, drag files in and out, etc.), except that everything inside it happens to be stored on a server in some anonymous data center far away. As I discuss later in Local vs. Cloud Data Storage, keeping data in the Cloud also enables mobile devices to be more useful, even with much less internal storage than laptop or desktop computers.

Since your files are in the Cloud anyway, secondary tasks (like syncing them to other devices or sharing them with friends) become that much simpler. And some cloud storage services go considerably farther by adding more features, security, and flexibility.

In this chapter, as in many of the following ones, I’ll begin by laying out the important considerations and then offer some specific suggestions at the end (see Joe’s Recommendations: Cloud Storage).

Cloud Storage Basics

Copying files to a server somewhere—whether that’s a single computer or a virtual server distributed over numerous computers and locations—is a pretty straightforward task. What makes cloud storage different from merely storing files on a remote file server is that cloud storage usually involves most, if not all, of the following features:

• Redundancy: Each file is stored not just on one disk attached to one server, but in multiple places (to guard against hard drive failures, accidental file corruption, and suchlike).
• Flexible storage space: Most providers offer a modest amount of storage space for free (or very inexpensively) and let you pay for additional space as your needs grow.
• Desktop and mobile integration: Unlike the old days in which you had to use a special app like an FTP client (or even, gasp, a Web browser) to upload files to a server, modern cloud storage services almost invariably offer software that integrates with popular platforms, enabling you to interact with your remotely stored files as easily as local files. Most cloud storage providers have software for at least macOS, Windows, iOS, and Android.
• Data preservation: Cloud storage services usually have internal backups that enable them to restore their customers’ files even if a glitch wipes out all the redundant live copies on various hard disks. Whether you, as a user, can retrieve such backups is another question; see Backup, ahead.
• Encryption: Although sadly not universal, encryption is quite common among cloud storage services. Your files are generally encrypted before they leave your device, and remain encrypted in the Cloud. (As I explain later, in Security Overview, encryption isn’t a guarantee of security, but it’s an essential component.)
• Delta encoding: Suppose you upload a big file to the Cloud, and then later change only a tiny part of it. Will you have to upload the whole thing again? In order to save time, preserve bandwidth, and conserve storage space, cloud storage providers typically use a process called delta encoding (also known as block-level or byte-level incremental updates, among other names) to upload only the portions of files that change from one sync or backup to the next.

Beyond those basics, providers spin their services in numerous different ways, as I discuss next.

Cloud Storage Capabilities

When comparing different cloud storage services, you’ll find a wide range of features offered. However, there are three capabilities fundamental to cloud storage: syncing, sharing, and backup (see Figure 5). Some providers offer just one or two of these; some offer all three.

Syncing

When a cloud storage service offers a syncing capability, it copies files from your local device (computer, smartphone, etc.) to the Cloud, and keeps those files in sync automatically whenever they change (including adding or deleting files in designated places, such as a specific folder). Then, if you connect to the same service with the same account on another device, it copies the files to that other device as well. You can continue adding devices with the result that, no matter what device you happen to be using when a file is added, changed, or deleted, that change propagates automatically to the Cloud and, from there, to all the other devices in your account.

That’s a general description; the details vary. Some services sync only the files in a designated folder, while others let you choose arbitrary files and folders to sync. Some perform the sync automatically whenever files change, while others follow a fixed schedule. Some duplicate all your files across your devices, while others cache only a portion of your data and download whatever else is needed on demand.

Beyond normal syncing of files and folders, some cloud storage services offer application programming interfaces (APIs), which are low-level hooks that let third-party developers integrate syncing support directly into their desktop or mobile apps, often for the purpose of storing and syncing data that doesn’t take the form of standalone documents.

Sharing

Virtually all cloud storage providers let you share any file that you’ve uploaded with other people. Sharing can take numerous forms, and the exact range of features varies by provider. Here are some common options:

• Individual files: When you share a file, you get a URL that anyone can use to download it (or, in some cases, view it in a Web browser). Some providers let you restrict access to only certain people, or protect shared files with a password.
• Folders: You can often share an entire folder too. Folder sharing may require that the other participants also have an account with the service and install the service’s software on their devices. Services vary as to whether you can offer participants read-only or read-write access, and the granularity with which you can tailor file and folder permissions.
• Photos and videos: When you sync a folder full of photos and videos, you may be able to display it as a Web-based photo album. In some cases, you can even invite other people to add their own photos to your album.
• Collaborative editing: Providers who offer both cloud storage and Web-based editing apps usually combine the two in one way or another. Often, you can share a file in such a way that multiple people can edit it at the same time in a Web browser.

One thing to keep in mind is that sharing files is somewhat at odds with encryption. For example, let’s say I’m using a super-secure syncing service that encrypts files on my computer and keeps them encrypted in the Cloud, perhaps even in a way that doesn’t permit the provider to read them. That’s great, but if I share a link to the file, the people I’m sharing it with must be able to see the unencrypted version. That, in turn, means the provider must have the capability of decrypting at least that one file. In other words: assume security ends where sharing begins.

Syncing and sharing almost always go together. In particular, it’s rare to see a cloud syncing service that doesn’t also offer some form of sharing.

Backup

You’ve synced a bunch of files to the Cloud. That means you have a backup, right? Well, not necessarily. Some cloud storage providers offer genuine backup capabilities, while for others it’s merely an afterthought with a list of gotchas.

Backup is fundamentally different from syncing. With syncing, all changes are supposed to appear on each side. So if I accidentally delete a chapter from my novel and then sync that file to the Cloud, guess what? The synced copy is also missing that chapter. And, if I delete an entire file in a folder that I’m syncing, that file is usually removed from the cloud storage as well. In both cases, syncing doesn’t function as a backup, because it doesn’t let me get my deleted data back.

However, some cloud storage services offer versioning, which means storing not only the most recent version of every file but also past versions. Often, this includes retaining copies of files you’ve deleted locally, at least for a while. Providers may limit how long older or deleted files are retained. But if not, or if the limits are generous, the cloud-based copy of your files can function as a backup of sorts. (Be that as it may, I would never recommend this type of file storage as one’s sole means of backing up data.)

Cloud storage providers that specialize in backup rather than syncing and sharing are more likely to offer plans with unlimited online storage space. And that’s handy, especially when you’re storing multiple versions of every file!

Even then, cloud storage nearly always backs up only certain folders, not everything on your device—and it invariably takes much longer to back up data to the Cloud than to a local hard drive or SSD. So I tend to think of cloud backup as a useful addition to local backups rather than a replacement.

When it comes time to restore files that you’ve backed up to the Cloud, some backup-oriented services make it easier than others. Finding the particular version of a particular file is sometimes challenging, and the software may or may not restore the recovered files to their original locations.

I go into much more detail about backing up files to the Cloud in Cloud Backups, a bit later in this book.

Example Cloud Storage Providers

Cloud storage providers seem to multiply like tribbles—they also frequently add features, increase available storage, and lower prices to compete with each other. I wouldn’t even attempt to compile a complete list. And, as I pointed out, many storage providers offer multiple capabilities, but aren’t equally strong in all areas.

Just to give you a flavor of what’s out there, I’ve selected ten representative providers that focus primarily on syncing and sharing, or for whom syncing and sharing is on par with online backups. (Later on, in Backing Up Stuff to the Cloud, I list providers that focus primarily on cloud backups.) For an even longer list, consult the online appendixes for my book Backing Up Your Mac: A Joe On Tech Guide.

Here, in alphabetical order, are ten of the more popular choices:

• Amazon Drive: 5 GB free; $11.99 per year for 100 GB; $59.99 per year for 1 TB; and $59.99 per additional TB, up to 30 TB total. (Before June 8, 2017, Amazon Drive offered unlimited storage for $59.99 per year.)
• Box: 10 GB free; paid plans start at $10 per month for 100 GB.

• CloudMe: 3 GB free; paid plans start at €1 per month for 10 GB.
• DollyDrive: No permanent free storage, but there’s a 14-day free trial. Pricing starts at $5 per month for 500 GB. Mac and iOS only.
• Dropbox: 2 GB (or more) free; paid plans start at $9.99 per month for 1 TB.
• Google Drive: 15 GB free (shared among Google Drive, Gmail, and Google+ Photos); paid plans start at $1.99 per month for 100 GB.
• iCloud Drive: Part of Apple’s iCloud service. Includes 5 GB of storage free (shared among various services). Additional storage (which can be shared with family members) is available at $0.99 per month for 50 GB; $2.99 per month for 200 GB; or $9.99 per month for 2 TB.
• Microsoft OneDrive: Formerly known as SkyDrive. 5 GB free; paid plans start at $1.99 per month for 50 GB.
• SpiderOak ONE: No permanent free storage, but there’s a 21-day free trial; paid plans start at $5 per month for 100 GB.
• SugarSync: No permanent free storage, but there’s a 30-day free trial. Pricing starts at $7.49 per month for 100 GB.

Every one of these services has something going for it, and I have had at least free accounts with almost all of them. But price and storage space are only two of numerous factors you should consider when choosing a cloud storage provider.

Other Cloud Storage Factors to Consider

You probably noticed in the list above that the amount of storage you get per dollar varies wildly from one service to the next. For example, leaving aside annual discounts, special promotions, and the like, 1 TB of cloud storage would cost you about $10 per month with Dropbox (my personal favorite), but just $5 with Amazon Drive. So…case closed, right? Surely I’m insane for paying twice as much as I have to for storage space.

Well, I can’t rule out insanity, but there are other things to consider when choosing a cloud storage provider:

• Desktop and mobile app support: Some apps bake support for certain cloud storage services right in, often by using low-level syncing APIs. For example, a couple of my favorite apps for Mac and iOS (I’m thinking particularly of 1Password and DEVONthink, both of which I use many times a day) have built-in support for syncing data via Dropbox or iCloud—but not, say, Amazon Drive or Google Drive. In fact, as I look through the various services directly supported in the apps I use on each platform, Dropbox comes up far more often than any of the rest. See which services your own favorite apps support, and factor that into your decision.
• Web support: Can you access your files in a Web browser—for example, if you need a file while away from your own computer? Most services offer a Web interface, but not all are equally flexible or easy to use. Some cloud storage services, on the other hand, go even further by offering Web-based editing apps—for example, you can use Google Docs to edit word processing files stored in Google Drive, or Office Online to edit spreadsheets stored on OneDrive.
• Performance: To some extent, there’s a correlation between cost and the rate at which you can upload or download data. Although many factors affect performance, I’ve heard anecdotal reports that, for example, Amazon Drive tends to be much slower than services like Dropbox and Box, which could partially explain the cost differences.
• Syncing vs. caching: Most services sync your files across all your computers (although perhaps not mobile devices, which usually have less storage space). That means you can work with any of the files even when you’re offline. But iCloud Drive, for example, optionally removes local copies of files if you start running low on disk space. That’s useful for what it does, but if you don’t happen to have a local copy of a file you need and find yourself without a reliable Internet connection, it could be a problem.
• Security policy: We’ll come back to this in the chapter Security in the Cloud, but do read up on what the service says about security. Does it encrypt files on your device, as well as in transit? Does the provider hold the encryption key, or are you the only one who can decrypt your own files?
• Popularity: What do your friends and colleagues use? If you want to share files with someone (or vice versa), it’s usually easiest if both parties already have an account with the same provider. Telling someone they can share a folder with you, but only after they create an account and install some software, isn’t very user-friendly.
• User experience: If you sign up for free accounts or limited-time trials to test cloud storage providers, pay attention to the steps you have to go through to transfer and share files, the user interface of the apps you install on your devices, and how it feels to interact with the service overall. For example, even though SpiderOak ONE’s specifications look fantastic, I don’t enjoy using it; I find the user interface to be unattractive and unnecessarily complicated. It just doesn’t seem as simple or direct as Dropbox or Box. I’m not trying to talk you out of SpiderOak ONE, by the way, only pointing out that it’s worth paying attention to your personal tastes and preferences.

Figuring Out Where Your Data Is

Before we get to my recommendations for cloud storage providers, I want to take a brief detour. No matter which cloud storage service you use, it’s a fairly safe bet that whatever data you sync is stored in the cloud—hence the name! But the more interesting question is whether that data is also on your Mac, PC, or mobile device. The answer may surprise you.

Most cloud storage services keep one or more folders in sync between your computer and the cloud (and, in many cases, store copies of older versions and deleted files, but only in the cloud). So, in general, if you see a file in one of these synced folders on your Mac or PC, it’s there—but it’s also in the cloud (and vice versa). But there are exceptions. For example:

• Selective sync: Dropbox and a number of other cloud storage services let you opt not to store certain items on any given device—they’re still stored in the cloud, as well as on devices where you didn’t opt out, but just not here. You might do this, for example, if you have a laptop with a very small SSD and you don’t have space for a local copy of every file that’s in your Dropbox. The point is, with selective sync features, you may have files in the cloud that do not have local equivalents.
• Manual or intelligent caching: Some cloud storage apps—especially on mobile operating systems—assume you don’t want local copies of everything, but only those items you expressly ask for or actively use. So some of them let you mark items you want to sync locally, while others try to anticipate what you want and figure it out for you. In either case, there’s no guarantee that any particular file you may want will be loaded on your device at a given time.
• iCloud optimized storage: iCloud offers a feature called optimized storage, which you can enable or disable separately for iCloud Drive (including your Documents and Desktop folders, if you choose to sync those via iCloud) and for photos in the Photos app. When this feature is turned on, your Mac or iOS device normally stores full copies of all your files or photos. But if you start running low on disk space, macOS or iOS will silently delete local copies of some of the items to save space while keeping the originals in the cloud. For regular files, you still see an icon; double-clicking it causes the original file to download and open. For photos, you still see a thumbnail; opening it causes the full-resolution version to download. But, you have no way to control which files are stored locally; the whole process happens invisibly in the background.

Even with a feature like manual caching or iCloud’s optimized storage, if your computer is always connected to the Internet via a reliable, high-speed link, the location of your files may be irrelevant. Whether they’re on a local disk or in the cloud, you can see them, open them, edit them, and save them—the difference is often imperceptible.

But, the actual locations of your cloud-synced files could become quite important in a few situations. For example:

• Backups: Some backup software backs up only files that are stored locally, not files on local or remote servers. If you want to be sure your files are backed up, it’s important to know where they are and whether this limitation applies. (Any files your cloud storage service syncs to your computer are, by definition, stored locally and are therefore available to your backup software. Files stored only in the cloud are generally inaccessible to backup apps.)
• Offline access: What if your ISP has an outage or someone inadvertently cuts a cable, and you’re without Internet access for a day or two? What if you’re traveling somewhere without Wi-Fi or a reliable cell signal? What if your only means of Internet access is a slow dial-up connection? Even the most wired person may, on occasion, need to access files without an Internet connection.
• Limited storage: Smartphones, tablets, and ultralight notebook computers often have a lot less storage than desktop computers and full-size notebooks. To maximize free space, you may be tempted to delete documents from a cloud-synced folder, assuming that you’re removing only the local copies and that the originals will still be in the cloud. Sometimes that assumption will be incorrect!

I can’t tell you for certain exactly where all your files are. Every cloud storage service and app has its own way of doing things, and you may need to consult the documentation for the one you use to determine the default behavior and what your options are.

However, I can offer a quick tip. If you’re unsure whether a certain file has a local copy or is stored only in the cloud, disable Internet access on your device completely—that is, turn off Wi-Fi and cellular data and unplug the Ethernet cable, if any—and try to open that file. The fact that a filename or icon shows up in a list doesn’t guarantee that you have a local copy, but if you can actually open it without network access, then you do! (And if you don’t, that’s the time to consult the provider’s Web site to see how you can make that happen.)

Joe’s Recommendations: Cloud Storage

Given all the factors I discussed in this chapter, what’s my recommendation for cloud storage? If I had to pick just one cloud storage provider—at the moment—it would be Dropbox. It’s simple, fast, and reliable. Dropbox excels at syncing, is pretty good at sharing, and offers versioning, which can serve as a limited form of backup. Even though it’s not the cheapest, it has the broadest third-party support, particularly in iOS apps, and more of my friends and colleagues use it than any other service. I like it enough that I wrote a whole book on it: Take Control of Dropbox. But as with all cloud providers, my recommendation could change in the future.

Furthermore, because the range of features each service offers overlap only partially, most people will probably need more than one cloud storage service. For example, you might need Dropbox for some things, iCloud for something else, and Google Drive for still other things. And, if you’ve decided to go all in with a particular ecosystem (such as Apple’s, Google’s, or Microsoft’s), then using that provider for cloud storage might be the wisest decision even if, considered in isolation, a different provider would be the natural choice.

Of course, you’re free to use as many different cloud storage providers as you like. But don’t go crazy, because each one adds to the amount of complexity you have to manage (see Storage, Sync, and Backup Services for considerably more detail on this topic). In particular, avoid syncing the same files or folders using multiple services. In my experience, that causes no end of problems (but if you’re determined to ignore this advice, see the sidebar ahead for apps that may help).