Literally every single thing will be erased all data, all files, all applications, all photos, all movies, every single thing on the computer will be erased. Remember that performing a clean install erases everything on the Mac. This is usually a lengthy process that should not be taken lightly and without a proper time commitment.

We’ll break up the clean install process into five main steps: backing up the Mac and all important data, creating a bootable installer drive for High Sierra, erasing the Mac, running through the MacOS High Sierra installer onto the freshly blank drive, and then manually restoring your data, apps, and files. How to Perform a Clean Install of MacOS High Sierra Any failure to sufficiently backup data will lead to permanent data loss. A clean install is best used for specific reasons by advanced Mac users who have the capability and patience to perform these actions competently. Additionally, performing a clean install can be a cumbersome and time consuming process that involves a lot of manual intervention with app installs, manual data backups, and then specific data restoration, which is why most users avoid the clean install process and simply choose to update and install macOS High Sierra as usual. Important note: A clean install requires the Mac hard drive to be erased, meaning all data, files, photos, movies, apps – everything will be erased from the computer. This tutorial will walk through how to perform a clean install of macOS High Sierra (10.13+).

Cleaning macbook pro hard drive