How much space is used for mounting and the OS?

Discussion in 'iMac' started by aman88, Apr 28, 2019.

  1. aman88 macrumors member

    Mar 21, 2019
    Looking to get the 256 gb ssd iMac... I was wondering how much space is there standard taking into count the mounting of the disc and the OS?

  2. mikehalloran macrumors 65816

    Oct 14, 2018
    The Sillie Con Valley
    On my system, 305GB. 810GB if I left my iTunes library on my boot drive (more on that below).

    Most people do not take account that Applications should remain on your boot drive and quite a few will not run properly if installed anywhere else.

    Although it is possible to pare my requirements down to a 1TB boot drive, it would take up too much time for me to swap my active work files in and out to externals. Life's too short.

    2TB on board is my sweet spot between time spent on housekeeping and the huge cost of going to 4TB on my iMac Pro. I can do this only by taking advantage of the ability to offload my iTunes (500GB) onto an external in Mojave.

    Offloading iTunes is possible in earlier Mac OS using Symbolic Links. Not as easy as in Mojave but the results are the same:

    If this makes it easier for you to save money with a 256GB, then that's ok, too.

    Many of the armchair experts around here will immediately tell you to get the 512GB system. That's not wrong when you're considering a 256 but they're not right either when no one really knows your needs—including me.

    None of us are you. Do more research. Ask more questions if you must but tell us about yourself, how you use a computer, what apps you run now and what you'd really want a new iMac to do with you at the helm.
  3. aman88 thread starter macrumors member

    Mar 21, 2019

    On my 2010 iMac I have 924/1024 gbs left lol... I meant I know when a hd says 256 gb you do not get the full amount because some if taken away (out of the box) by the OS and mounting. I was just curious how much of a standard deduction there is out of the box on a ssd drive?
  4. nouveau_redneck macrumors 6502

    Sep 16, 2017
    My OS and system areas running Mojave are currently using ~35 GB.

    That sum includes all content under:
    - and the remaining hidden folders.
    - it also includes the approximate amount of the /Applications folder that is taken up by macOS applications.

    Keep in mind that as applications are installed, cloud services used, etc. the system space usage will increase. For instance, I have ~2.5 GB of iCloud Notes taking up space within the number I quoted above. Applications will have libraries within that space that will also have varied usage, that are hard to accurately.

    One of the biggest variables will be if you are using Time Machine which creates and stores snapshots in your system area. When I was using time machine, it was common for me to have ~20 GB of space for those snapshots on my drive. I've read posts here where people have much more than that used by snapshots.
  5. fisherking macrumors 604


    Jul 16, 2010
    ny somewhere
    i've got 250GB on my 12" macbook. applications folder is 7.5GB, and the combined OS/library is just under 11GB.

    you'll be ok if you're not doing video or pro audio work, and your pictures (and music library) are manageable... (my itunes is 19GB, photos is 6GB). so, right now i have 121GB available.

    really depends on what you're going to do with the imac. and, of course, you can always get an external drive to store work, old work, etc.
  6. aman88 thread starter macrumors member

    Mar 21, 2019
    Thank you for posting that it makes sense... I do my own back ups to my external 1 tb hard drive and do not use time machine or iCloud...
    --- Post Merged, Apr 28, 2019 ---
    This scenario sounds more like what I have thank you!
  7. mikehalloran macrumors 65816

    Oct 14, 2018
    The Sillie Con Valley
    As you have seen, the original question is meaningless out of context.

    We all want to save money but there are times when a small savings costs more down the road.

    No one thinks, 'maybe I got too much' six months later when they're enjoying the new machine and it does what they want. If, however, things take too much time and you learn something could be avoided by spending $xxx more, you'll think about that a lot. I know this issue first hand.

    Case in point: For $180 more, I could have bought my wife an i7 iMac instead of an i5 in 2011. I was happy with my 2010 i7—great machine. All my apps ran well. New models came but I was good... We both make our livings on out iMacs, btw.

    Then I discovered that my core app was sloooooow on an identical i5 in a studio where I was doing contract work. Huh? I then A/B'd with hers — it was not an anomaly. Ok, no big deal, runs fine on mine right?

    Well... my situation changed and I really needed to run a pair of side monitors but the 2010 can only handle one unless you use a DisplayLink box, not a great option in 2013 and even worse later when Apple killed support in OS 10.13.4–6 (though they bought it back in Mojave, the 2010-11 iMacs are incompatible). Ok, swap with my spouse (she was ok with it) and run two monitors through the TB ports—problem solved, right? No. As the years progressed, my core app ran even worse on her i5 so I was out of luck. All because I wanted to save a lousy $180 in 2011.

    Before someone with a good memory busts me on the number, the $180 difference was correct through the EDU store in 2011 while being $200 otherwise.

    Had I spent the coin, I would have made the swap in 2013 and neither of us would have thought of it again.

    I'd still need a new iMac in 2019—another core app requires Mojave. With my new machine, that $180 will fade into a distant memory.

    I already know that once she sees her work on my 5K display, she will want to jettison that 2011. Ok. She'll never need an iMac Pro but anything I buy for her will now be something I could use in a pinch if necessary.

    Lesson learned.
  8. Zandros macrumors member

    Sep 1, 2010
  9. mikey8811 macrumors member

    Mar 23, 2019
    That's what I do. BUT I think you have to put symlinks to move the backup of your iPhone that is done through iTunes. I have done this before on Windows but not on a Mac and am unsure if it works. I have a friend who tried doing it on Mojave and could not get it to work.

    I am in the same boat as the OP and have just ordered a 256 Gb SSD on the 27 in base iMac. I will put all my data ie. iTunes library and photos on an external HDD.
  10. Fishrrman macrumors P6


    Feb 20, 2009
    OP asked:
    " I was wondering how much space is there standard taking into count the mounting of the disc and the OS?"

    When I set up my 2018 Mini to boot and run Mojave UNDER HFS+, one of the very first things I did was to create a cloned archive of the Mini's original APFS Mojave install, essentially "untouched".

    I just mounted that drive and did a "get info" on it.
    It shows 22.68gb "used".

    So I'll reckon that's about the "size of the OS", including Apple-installed apps, as it comes "out-of-the-box" from Apple.

    The OP was worried about getting a 256gb SSD in an iMac.
    This won't be a problem, so long as you are willing to use an external drive (an external USB3 SSD would be fine) on which to keep "large libraries" (such as movies, music, and photos).

    Be "critical" about what you keep on the internal drive.
    Don't fill it up with a lot of junk you'll never look at or use!
  11. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    A new Mac out of the box will use abut 20GB of drive space for the OS and included free apps.

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10 April 28, 2019