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.