Yosemite Clean Install - Two different installation routines?

Discussion in 'OS X Yosemite (10.10)' started by tumas, Oct 28, 2014.

  1. tumas macrumors member

    Oct 21, 2014
    I did a few clean installs of Yosemite the past couple of days (on 3 different machines) and i did notice one really strange thing:

    1st installation routine:
    If you download the installation files, put them on a clean usb drive and start the installation, there will be a small little window with 4 choices what to do (e.g. disk utility, start installation etc.). If you choose to erase the disk with the disk utility and start the installation afterwards, it will show you how much space is on your HD and the installation begins. But this way the installation actually takes really a long time (12 minutes counting down) and the system will restart back into the installation and again tells you something about 12 minutes until it is finished. After that it restarts a second time and Yosemite will boot up.
    So all in all this way the installation takes about 30-40 minutes on a MBPr 15 2014)

    If the usb drive was previously used to do a clean install of Yosemite (e.g. on a different system), the first screen when booting from the usb-drive will look different. There will a "bigger" window with greetings to the installation and you can choose to use the disk utility only if you click on the top bar of the screen. (the window with the 4 options from the 1st method does not show up at all)
    When starting the installation this way, it will not show you the space of your hard drive and the installation again shows about 12 minutes to be finished.
    After that, the system reboots and Yosemite boots up.
    The installation this way is faster than the 1st and takes about 15-20 minutes.

    In my opinion this i quite strange. It seems like as if the installation files have to be written to the usb drive itself (which obviously happens during the very first use of the usb drive for an installation of Yosemite). But that doesn't make sense, does it?

    Anyone else noticed this kind of "issue" and have an explanation?

    PS: I hope i described the problem good enough with my basic school english ;)

  2. Tankmaze macrumors 68000


    Mar 7, 2012
    Yes, you are not alone.

    I also notice this when I installed it on my mbp. Did a TM backup, and since yosemite is a new look I might aswell did a clean install.
    The first boot / clean install it shows those box with 4 option inside, like restore from tm, install osx, disk utility, and I forgot the last one.

    This first one took a bit longer, stuck in the one second remaining, which by looking at the log the installer is verifying the dmg file.

    After install, play around with it and do some of installation of apps to determine its working or not. Once I know which app works, I plan to do another clean install.

    Boot again from the usb, and the box with 4 option gone. Only continue to install osx, and I use disk utility from the menu bar.

    No idea why it would have different setup but my guess is that the first installation is where the installer verifying the dmg, and it was a one time thing.
  3. hutrebug macrumors regular

    Jun 24, 2015
    Man this thread was really what I was looking for. Had the same experience while installing Yosemite on two Macs, that there are two different installation routines.
    Searched the internet but didn't find anything till this thread came up. Glad, that I'm not the only one, who experienced this thing, and it's apparently not a problem.

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