What's the best way to clean install (not upgrade) OSX (from 10.10 to 10.11) without formatting my drive?

This is a MBPr with a 1TB internal, where I have 700GB of media that I would like to leave on there, all within 2 folder at /

Can I just delete everything except those 2 folders then install OSX?

I'm thinking I have 2 options:

  1. Boot from a bootable USB with 10.11 installer
  2. Boot from a CCC clone external of my system drive

... and then delete everything except those 2 folders, then run the OSX installer.

  • 1
    A clean install means removing all that was there before - which is in effect formatting the drive - why don't yon want to do this?
    – mmmmmm
    May 3, 2016 at 8:21
  • 1
    Because I have lots of media files (700GB) in a root folder which would take a long time to backup & restore.
    – d0g
    May 3, 2016 at 8:34
  • This data is obviously important. I don't advise taking shortcuts - if it take a long time, then let it run overnight.
    – Allan
    May 3, 2016 at 8:53

3 Answers 3


There is no easy way to do this. You can't clean install and keep your files because those files live as part of the OS. The OS knows where they are, what they are, the permissions etc. Clean installing would be removing all parts of the OS and installing a the new OS and the links to those files, where it would not know it needs those files or what they are.

Alternatively you can try:

  • Create a New Partition (Say of 200GB)
  • Install a clean copy of OS X there
  • Copy 100GB of your files to the new partition
  • Delete those exact files on the old partition
  • Shrink old partition and expand new partition
  • And repeat last 3 steps till you have all files

But the best solution would be:

  • Buy external HD
  • Copy all files to external
  • Reinstall OS X
  • Copy files back

If you are trying to preserve files, formatting is not your answer. I suggest an "in place" install buy simply downloading the El Capitan installer (or applicable OS) from the Mac App Store. This will download the installer and you may simply re-install the operating system. Leaving all your home folder and additional files intact. This can be achieved by creating a media installer using terminal. You may refer to this Apple support article for a step by step.

  • He is on OS X 10.10 and he wants to be OS X 10.11 without doing an upgrade, but a clean install.
    – Chris
    May 3, 2016 at 15:06

The only thing I can suggest is to boot to the Recovery partition (⌘ Cmd+R), and do the command in Terminal (Utilities > Terminal):

sudo rm -r /folder_name

On all folders that you don't want to keep.

(Be carefull when you target your folder, NO RECOVERY possible. Check manual to be sure)

I'm pretty sure that the installing will not erase the data in folders you kept.

Or you also try to make another partition on your disk with the disk utility, then install OS X in the new partition, and remove all files from the old OS X installation.

  • 1
    Why Linux Live? I could do the rm even from the installer > utilities > terminal
    – d0g
    May 3, 2016 at 8:34

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