Reinstalling OS X from scratch

Discussion in 'macOS' started by tomf, May 3, 2013.

  1. tomf macrumors regular

    Nov 11, 2009
    Hi All,

    I'd just like to ask a couple of questions about completely wiping my mac pro and reinstalling OSX so it's like brand new.

    My details are -

    Mac Pro - Late2007/early 2008 model
    Current OS - OSX 10.7.5
    Processor - 2 x 2.66ghz dual core intel xenon
    RAM - 13GB
    2 additional internal hard drives (system drive is the standard one that came with it)

    I feel like my mac has become really sluggish over the last few months, it's never had a clean install since i purchased it.

    My main use of the mac is for writing music, so i know it's going to take a long time to reinstall a lot of the software, thats ok.

    Main questions really are, how do i best proceed now? What's the best way to wipe the drive and re install?

    Any additional things i should look at or do?

    Thanks for any help and advice,

  2. benwiggy macrumors 68020

    Jun 15, 2012
    You don't need to do a wipe and reinstall. I ran my last Mac for over 6 years without a clean install.

    1. Most of the system files are read-only and don't get altered, so reinstalling them achieves nothing.
    2. With a clean install, you plan to wipe the disk, and put back everything, except the bits that were giving you trouble.
    3. It's quicker to do it the other way round: just remove the bits that were giving you trouble! :D

    First, make sure you haven't got any software installed that is running in the background, anything patching the OS, etc, etc.
    You can usually find these in System Preferences > Users & Groups > Login Items; also the top level /Library subfolders LaunchAgents and LaunchDaemons.
    Next, do a Safe Boot. This will clean various caches and run a minimal system. See if things are better now. (You will want to reboot normally shortly after this.)
    Next: create a brand new user account and test the problem there. If everything is better in the new user account, then your problem is in your original account. (So no need to reinstall anything!)
    Don't be tempted to move everything to the new account: you just need to delete some things in the old one.
    You may find that preference files have got corrupt, and so you can try removing .plist files in <user>/Library/Preferences for various related things. You can always replace them if no benefit is found. You may need to log out and in to test the effect.

    Lastly, you should get utility software like Onyx. This is very good for troubleshooting when you have a problem. (You do not need to run any of it regularly for maintenance.)
    It has a range of utilities, including cache emptying, preference checking, rebuilding of various databases and indexes, which you may want to try.
    It is of course very powerful and you should make sure you have a backup before proceeding.
  3. tomf thread starter macrumors regular

    Nov 11, 2009
    Thanks, I do see what you're saying, but I haven got a specific problem as such.
    By the sounds of your post it sounds more trouble to do all that (I.e deleting files, creating new accounts, seeing if that helps, going back, delete other files etc) than to just do a fresh install.
    I just feel like a total fresh reinstall would be better.
  4. benwiggy macrumors 68020

    Jun 15, 2012
    At the very least, I would suggest emptying your caches and seeing if that improves things. Corruption in the caches is a likely cause of sluggishness.

    OK. You will need to:
    1. Wipe the disk.
    2. Reinstall the OS.
    3. Reinstall any apps that have installers.
    4. Restore any other apps from backup, App Store, etc.
    5. Restore your user files.
    6. Don't restore your User account preferences, as that may be the source of the problem.
    7. Recreate your preferences and settings for every app and part of the OS by hand, or manually sort out which preferences to include, testing whether they affect performance.

    On Windows, it seems like a clean install the first thing you do when you get a problem. On a Mac, it's the last.
  5. tomf thread starter macrumors regular

    Nov 11, 2009
    Thanks, when you say restore user files, what do you mean? things like documents, pictures etc?

    I don't plan on restoring anything, i plan on just re installing stuff - e.g music making programs etc....(i use my mac pro for making music).

    I'm treating it as if i had just bought it brand new.
  6. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    Since you are running Lion, this is very easy. Just command-r boot to the recovery screen then start Disk Util and erase Macintosh HD. Then quit Disk Util and click install OS. You will be asked for the AppleID you used to buy Lion, then it will DL and install the OS. Takes a bit for the 4.7GB DL to finish.
  7. benwiggy macrumors 68020

    Jun 15, 2012
    Yes, I mean any "application documents" you have created or downloaded.

    If you are going to create a "virgin" state, then fair enough. It will still be a significant amount of time to do all that.

    But next time you get some sluggishness, don't be tempted to do it again!

    I've owned or been responsible for many Macs running OS X over the last ten years and I've never done a clean install for anything except:
    1. installing OS X on a new hard drive;
    2. rolling out a complete new image of system disk, complete with apps.
    3. downgrading after a Snow Leopard update had a massive bug in it.

    I've never felt it necessary to "nuke and pave" just for sluggishness or other issue.
  8. woodNfish macrumors newbie

    May 8, 2013
    I don't have an original OS, what do I do?

    I also have a late 2007 macbook pro that I got at the dump. The original HD was gone so I bought a new one and installed it and a charger. Today a friend loaned me Snow Leopard and I tried to install it but got this message:

    "Snow Leopard requires Mac OS X 10.5 or later to already be on the system"

    Well, there is no OS on the system, no backup, nothing. How do I install an OS on a bare system? Do I just need a current OS with an install disk or something? Or do I have to install an earlier OS (which one?) and upgrade to the most current?

    Any help is greatly appreciated.
  9. 8Apples macrumors member


    Nov 1, 2013

    Wow, thanks for this advice! I stumbled upon this thread, because I was going to nuke and re-pave. I have been experiencing some serious slow downs, to the point, I'm wondering if I have hardware RAM issues. I'm going to run through these steps. Is there a way to troubleshoot the RAM, and be sure it is good? I don't live close to an Apple store at all.


    PS - I really had to comment on this thread so I wouldn't lose it. Besides, I think I stumbled on some real quality, qualified advice here, from an experienced user.
  10. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    Run the Apple Hardware Test.
  11. 8Apples macrumors member


    Nov 1, 2013
    Actually thanks to the OnyX posted earlier here, I found the issue. As per Apples Support suggestion of running the Disk Utility and verifying my primary HD, it came up clean. No errors. However, I deleted a few old Prefs as per the steps laid out, and finally got to OnyX. Downloading, installing, and running it, it began diagnosing my computer. It said to reboot with Command-R, and to run the disk utility and repair my primary HD. I did so, it indeed fixed errors that had not been reported in Disk Utility when I ran it. Rebooted, and have lots of free RAM now, almost 1GB, compared to the 20MB I had been bouncing into.

    Thanks for the suggestions and help, even though I 'hijacked' a thread, it sure fixed my problem! I will keep in mind that link though if I ever think in the future I'm having Hardware issues!


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