Need help with a reformat / reinstall

Discussion in 'OS X Yosemite (10.10)' started by alldat, Oct 21, 2014.

  1. alldat macrumors regular

    Aug 10, 2008
    My Mac: MacBook Pro (15-inch, Mid 2009), Processor: 2.8 GHz Intel Core 2 Duo, Memory: 8 GB 1067 MHz DDR3

    Basically, I used disk utility for the first time in years today and it gave me a message along the lines of "this hd is corrupted, please restart holding command + r and repair disk"

    Did that, then got the message that the disk can not be repaired, that I need to reformat the drive. I'm pretty decent with computers but don't really do any super technical stuff with it. I just want to know the exact steps to take to reformat, and then I guess restore from my time machine backup? When I do this, is my mac going to be exactly like the way I backed it up?

    I'm also confused as to what is corrupt. The mac runs fine, maybe a little slow but thats's my fault for having so many tabs open and the battery is on its last legs. No crashes, no spinning rainbow wheel, everything works fine.

    Any help would really be appreciated since I don't want to screw this up and potentially lose any files. Also, if the hd is corrupt, does that mean my time machine back ups are also corrupt?

  2. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    Here is an easy way to go about this.

    I'm assuming here you are on Lion 10.7.2 or newer and your Time Machine backup is to a locally attached USB drive?

    Shutdown and attach the TM disk, then hold the option key as you power on. When the boot manager screen comes up select the orange USB TM drive to boot from.

    That will get you to a recovery screen like this.


    Now launch Disk Utility and go to the erase tab. Then select the drive brand name in the left column at the very top (above Macintosh HD). Now pick Mac OS Exteneded (Journaled) in the format dropdown and apply the change. This will reformat the entire disk.

    Now quit Disk Util then click restore from Time Machine and follow the prompts.

    That should fix you up.

    Afterwards, you may want to use Disk Util to do a verify disk every few days just to make sure you don't have disk errors reappearing indicating imminent drive failure.

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