In this respect, the OS X installer is just like any other app you buy from the Mac App Store. Like all recent versions of OS X, El Capitan is distributed through the Mac App Store: You download an installer app (called Install OS X El Capitan.app) to your Applications folder. And if your Mac is experiencing problems, a bootable installer drive makes a handy emergency disk. If you want to erase the drive on a Mac before installing El Capitan, or start over at any time, you can use a dedicated installer drive to boot that Mac, erase its drive, and then install the OS (and subsequently restore whatever data you need from your backups). If you need to install El Capitan on multiple Macs, using a bootable installer drive is faster and more convenient than downloading or copying the entire installer to each computer. In other words, you no longer have the same safety net or convenience.īecause of this, I recommend creating your own bootable El Capitan (OS X 10.11) installer drive on an external hard drive or USB thumb drive. But to install or reinstall a recent version of OS X, you must either download a non-bootable installer from the Mac App Store or (via OS X’s invisible, bootable recovery partition) download 6GB of installer data from Apple’s servers during the installation process. When OS X shipped on a DVD a good number of years ago, you always had the convenience of a bootable installer-an OS X installer that could be used to boot your Mac if its own drive was having problems.

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