Apple's OS X Yosemite for the Mac follows the tradition of providing an easy upgrade install as the default installation method. The process can be completed in just a few on-screen steps.
Before you launch the Yosemite installer, take a moment to ensure it is the right install option, that your Mac is properly prepped, and that you have all the information you will need at your fingertips.
Apple no longer offers Yosemite (10.10) for download. The information in this article is maintained for archival purposes.Coyote Moon, Inc.
How to Upgrade Install OS X Yosemite on Your Mac
OS X Yosemite (10.10) doesn't require any new or specialized hardware to work on most Macs. If your Mac can run OS X Mavericks (10.9), it should have no difficulty with Yosemite.
Once you're sure that your Mac meets the Yosemite minimum requirements, you're almost ready to proceed, but there are still a few more steps to take.
Back Up, Back Up, Back Up
You're going to be making major changes to your Mac—installing new system files, deleting old ones, applying for new permissions, and resetting preferences. There's a lot that happens behind the curtain of the install wizard. Should something occur during installation, such as a drive failure or power outage, your Mac may fail to restart or be compromised in some permanent way. To limit the risk of losing important data, make sure to back up your existing data before proceeding.
Types of OS X Yosemite Installation Options
Yosemite supports the usual installation options: Upgrade Install, which is what this guide covers, and Clean Install. The Clean Install option has some variants, such as installing on your current startup drive or on a non-startup drive.Upgrade Install: An Upgrade Install completely removes the existing version of OS X from the startup drive. It updates all needed system files and all applications that Apple includes with the OS, such as Mail and Safari. An Upgrade Install won't make changes to your user data; as a result, your user accounts and any data associated with them remain. However, when you first run an app, it is likely that your data will be updated to work with the newer version. For that reason, you should not expect to be able to return to the previous version.Clean Install: A Clean Install completely deletes all data on the target drive and replaces it with OS X Yosemite and the default apps that come with it. Selecting the Clean Install option leaves your Mac in a similar condition to the day you got it: no user data, no user accounts, and a setup wizard for creating your first administrator account.
A Clean Install is for starting from scratch. Before you decide to use the Clean Install option, be sure to back up all your data.
How to Start the Upgrade Install
The first step in installing Yosemite is to check your Mac's startup drive for any problems, including repairing permissions.
Yosemite is a free upgrade from OS X Snow Leopard (10.6) or later. If you're running a version of OS X that is older than 10.6, you need to install Snow Leopard on your Mac first.
Before proceeding, make sure you have a copy of OS X Yosemite (10.10)—either on a disc or as a download.
Access the Yosemite disc or a downloaded disk image to begin the installation process and follow the on-screen instructions.
When the Install OS X app opens, select Continue to proceed.
The Yosemite license agreement appears. Select Agree.
A window asks you to confirm that you read the license agreement. Select Agree.
Your Mac's startup drive will appear as the install destination for Yosemite. If this is correct, select Install. You can select Show all Disks to select a different drive location.
If you don't want to overwrite your startup drive with the new OS or any of the available drives, select Quit Install OS X from the Install OS X menu.
Enter your administrator password and select OK. The installer begins by writing needed files to the startup drive. This process can take a few minutes. When it's complete, your Mac restarts.
After the restart, your Mac displays a gray screen with a progress bar. Eventually, the display will change to show an install window with a progress bar and a time estimate.
Once the progress bar completes, your Mac restarts again, and you go to the login screen.
How to Set Up Yosemite
At this point, you've completed the upgrade install process. Your Mac has rebooted and is displaying the login screen.Coyote Moon, Inc.
Enter your account password and press the Enter or Return on your keyboard.
Yosemite displays the desktop along with a window asking you to log in with your Apple ID. You can skip this process if you want by selecting Set Up Later. You should sign in, however, because doing so makes the setup process move faster. After you entered your Apple ID, select Continue.
A drop-down window requests permission to add your computer to the Find My Mac service. Select About Find My Mac to view information about the service, Not Now to disable the service (you can turn it back on later), or Allow to enable the Find My Mac service.
A drop-down window asks if you agree to the terms. Select Agree.
The next step asks if you want to set up iCloud Keychain. You can select Set Up Later if you'd like to defer the process and then select Continue.
The Yosemite setup window displays a list of software that is incompatible with the new version of OS X. Any application listed is automatically moved to the Incompatible Software Folder, located at the root of your startup drive (/[startup drive name]/Incompatible Software/). Select Continue.
The installer completes the setup process. This usually takes a few minutes, after which the desktop appears, ready for you to use.
Now that you're running Yosemite, take a look around. Check out Safari, which is much faster than previous versions. You may find that a few of your preference settings reset during the upgrade install. If you bring up System Preferences, you can go through the preference panes and set up your Mac as you wish.