7 Replies Latest reply: Sep 8, 2013 2:37 PM by tal1971
tal1971 Level 2 (245 points)

Presently I have a Windows PC. Now with Windows, whichever version of Windows my pc has on it, if I later want to put a new OS onto it, I have to install the newer OS, but in doing that, it wipes the hard drive, which then means I have to reinstall all my program's and set them up to my liking etc.


I was wondering with Mac. If for example I had an iMac that had for example Snow Leopard, Lion. If I wanted to update the OS to Mountain Lion. Would upgrading to Moutain Lion wipe the hard drive and in doing that remove all my applications and anything else that had been installed?


Or is it possible with Mac to slip stream (for want of a better word) a newer OS onto the Mac and leave the applications etc that were previously installed intact and untouched?



Thanks in advance.

Windows Vista, iPad (3rd Gen) 32GB iPhone 4S 32GB
  • Don Archibald Level 10 (101,340 points)

    The default with Macs is that the installer will update just the OS (and perhaps a few standard Apple utility programs) and will leave everything else intact. The installer will not delete anything (other than OS files it is replacing) without your permission.


    It is always a good idea to have a backup of your data, in case there's an unforseen problem - such as the power going out in the middle of an update.

  • Eric Ross Level 6 (11,665 points)

    On a Mac OS update the update will not erase your data, only the Mac OS is updated all of your settings and programs will still be installed. 

  • tal1971 Level 2 (245 points)

    Thanks Don for the help it's greatly appreciated.


    Nice to hear that an OS update/upgrade is a lot easier on the Mac than what I'm used to with Windows.


    Thanks again.

  • tal1971 Level 2 (245 points)

    Thanks Eric for the help it's much appreciated.

  • tal1971 Level 2 (245 points)

    Just to update this post and ask another question


    In January of this year I bought my first Mac (Late 2012 iMac 27 inch) and I absolutely love it. The move from Windows to Mac has been an absolute pleasure and I only wish I'd done it earlier.


    To follow on from my original question:


    Some people recommend that when updating to a new OS, that its best to do a fresh install and in doing so erase all what's on the hard drive. The reason been is to replace any left over files that might cause issue or not play nice with the new OS.


    I was wondering if any of the long term Mac users could give their experiences of whether its best to just update the OS and leave everything else untouched and if they've done this have they had issues with leftover files etc from the old OS.

  • Old Toad Level 10 (135,314 points)

    I see no reason for a fresh install unless you're having problems with the old system.  I've upgraded from Leopard to Mt. Lion without a clean  install.  I've event reinstalled Mt. LIon from the Recovery volume when I trashed my Finder app trying some hacks.  The reinstall was easy and painless.



  • tal1971 Level 2 (245 points)

    Thanks very much for the help old toad.