This article will discuss a procedure which will allow power users to create a bootable installation disk for Mac OS X Yosemite. This means that most people with more than one Mac will end up spending time downloading the same file over and over until the job is complete. Within OS X Utilities, choose Reinstall OS X. Prepare a clean external drive (at least 10 GB of storage). The following method allows you to download Mac OS X Lion, Mountain Lion, and Mavericks. This is because after iTunes installs the latest OS, it deletes the file which was used to update it. Install older OS X onto an external drive.

iTunes makes it simple for users to download, install and forget, but it does not make it easy for those who have a number of Macs which they want to update.

One of the issues users face is the process by which Yosemite is updated. Obviously, this USB needs to be inserted into your computer when booting it. This is much different and tricky when comparing to Windows bootable USB. All you need to do is hold down the option key when you start the computer. A bootable USB is required in order to install macOS to repair the system or install macOS on a new Mac. Its a 16GB (USB 2.0) with the operating system already installed on it. If a Mac computer has the hardware to run Mac OS X Mavericks, then it also has the hardware necessary to run X Yosemite, with the exception in some circumstances being that some Mavericks machines do not have WiFi for the Continuity feature, which allows users to pick up where they left off using any of their Apple products. This USB will have a Mac OS with this bootable installer on it. Mac OS X Yosemite is available for free from the Apple iTunes store.

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