Make Final Preparations

Now that you know which basic installation technique you’re going to use, you’re nearly ready to proceed. Your next major step (which could take hours, or even longer) is to obtain the Sierra installer; then I’ll recommend a few other quick, last-minute tasks before you dive in.

Turn Off Anti-malware Software

In general, anti-malware software doesn’t interfere with purchases and upgrades from the App Store. However, when Apple released Mountain Lion, users reported that the Ad Banner Filter in Intego’s VirusBarrier software sometimes interfered with the process of downloading the installer. Something similar could happen again, and other anti-malware apps could also conceivably prevent Sierra from downloading properly. So, the easiest course of action is to turn off any anti-malware or ad-blocking software you may have until you have successfully downloaded Sierra, and then turn it back on.

Obtain the Installer

Depending on your situation, obtaining the Sierra installer may be a trivial matter of a few clicks, or it may be an involved ordeal.

Download Sierra on the Destination Mac

If you have a broadband Internet connection that can handle a 5 GB download, obtaining Sierra is just like downloading any other app:

1. Click the App Store icon in your Dock, click Featured, and locate macOS 10.12 Sierra (which should be displayed prominently).
2. Click Download.
3. If prompted, enter your Apple ID and password, and click Sign In.

The Sierra installer downloads to your /Applications folder—a process that could take anywhere from minutes to days, depending on the bandwidth of your broadband connection.

After it downloads, the installer launches automatically.

But we’re not ready to install Sierra quite yet, so choose Install macOS Sierra > Quit Install macOS Sierra to quit the installer for the time being; we’ll return shortly!

If the destination Mac doesn’t have sufficient Internet bandwidth, consider taking it to a library, coffee shop, friend’s house, the office, or somewhere else where you can use a higher-speed connection. If you take your Mac to a nearby Apple Store and download Sierra while connected to the store’s Wi-Fi network, the download will be ultra-fast, because it will come from a server within the store.

If your Mac isn’t portable enough to make that feasible, however, there’s another option…

Download Sierra on Another Mac

You need to get the Sierra installer onto your Mac somehow, but you need not download it from the App Store directly onto the Mac where you’ll install it. You can download the Sierra installer on another Mac, and then copy the installer to the destination Mac directly (over a network) or indirectly (by way of a USB thumb drive, a portable hard drive, or some other media).

Although there are many ways to do this, the basic steps you’d want to follow are these:

1. On the other Mac—the one where you’ll download the installer—open the App Store app.
2. Download Sierra, as described in the previous topic.
3. Copy the installer from /Applications onto the external media of your choice.

Copy the Installer to a Safe Place

Unlike most software that you download from the App Store, what shows up in the /Applications folder after you download Sierra is an installer (an application called Install macOS Sierra); you must run the installer to put all the necessary pieces in place. During this process, something surprising happens: the installer is deleted! That’s right—once Sierra is up and running, if you look in /Applications, the installer will be gone.

I presume the reason for this is that once Sierra is installed, Apple wants to give you back the 5 GB or so of disk space the installer was taking up, since you likely won’t need it in the future (and can download it again if you do). But what if you want to install Sierra on multiple Macs—or reinstall it later on the same Mac—without having to download that huge installer again? I’ll tell you what: you’d better put that installer in a safe place before you run it!

Now, before going any further, I should add some nuance to the “Sierra installer deletes itself” concept. The installer deletes itself only when both of the following are true:

• The installer is in /Applications on your startup volume.
• You do an in-place upgrade of your startup volume.

If you put the installer anywhere else—your Desktop, ~/Downloads, or wherever—it won’t be deleted after it runs. Even so, because that big file is valuable, I urge you to make a copy just in case the unexpected should happen.

So, before you do anything else, you should either Command-drag the installer to move it from /Applications to another location (so it won’t be deleted automatically, no matter what), or Option-drag the installer to copy it to another location—preferably another volume—so if it is deleted, you’ll have a spare. Or, create a bootable installation volume, as I describe next.

Update Your Duplicate (Again)

Earlier in this book, I instructed you to make a bootable duplicate of your startup disk and then—after performing some cleanup tasks—to update that duplicate so it reflects the current state of your disk. If you did that just minutes ago—and your bootable duplicate includes the Sierra installer file located outside of the /Applications folder—then you can move along to the next step. Otherwise, I suggest updating your duplicate one last time before running the installer.

Turn Off (Yes, Off) Automatic Duplicates

Picture this: shortly after you upgrade to Sierra, your backup software (which is still installed, natch) runs at its scheduled time, overwriting your bootable duplicate with a copy of your Sierra installation. And then, an hour or two later, you discover that Sierra has a major problem that requires you to go back to your previous version of OS X. But oops! The backup of your older system is already gone.

So, although you should certainly continue updating your duplicate after Sierra is installed, either do so using a new backup drive or wait a few days or so to make sure everything is working well enough under Sierra that you are unlikely to go back to your old system. Then, and only then, turn automatic duplicates back on.

Make a Copy of This Book

You’ll want to refer to this book while you perform your installation, especially if something goes wrong during the process. If you are reading on the Mac where you’ll be installing Sierra, if possible, you should either copy it to another computer, iPhone, iPad, or other mobile ebook-reading device, or print it.

For tips on transferring this book to a mobile device, read our Device Advice page (hint: popular methods include Dropbox and iTunes sync, as well as downloading directly to the mobile device from your Take Control account). To download a copy of the book in a different file format, click the link in Ebook Extras.

Or, if you print to paper, you can limit the printout to just these chapters (as appropriate to your situation): “Upgrade Using Plan A: In-place Upgrade,” “Upgrade Using Plan B: Clean Install,” “Perform Post-installation Tasks,” and “Troubleshoot Upgrade Problems.” If you are printing from the PDF version, you may also wish to print the table of contents.