thebeancounter13

Q: Unable to format partition

I have a late 2014 Macbook pro running 10.10.5 yosemite.

 

I normally always format my macs firstly by booting into the system mode (holding cmd + r) and then format a partition, then jump straight into the OS X installer.

 

Today i tried tried but when i jumped into the disk utility i had 2 items on the left sidebar, my usual HD, with the partition beneath, and then "disk 1" with "os x base system" beneath.

 

I tried to erase the partition (which i first had to unlock) and it gave me an error about spare volumes or something.

 

After clicking restart my issue is this:

 

My mac boots straight into the OS X utilities screen (i.e. no option to jump into my usual HD).

 

If i try and select install OS X, the only available partition to install onto is a "Recovery HD" which is just a 600mb volume which clearly isn't right.

 

if i jump into disk utility the options on the left for my HD are the HD itself (i.e. the partition which did show below no longer shows), but i cannot select erase, and cannot erase through the partition tab on this main volume. Ive tried verifying and repairing the disk and neither work.

 

Therefore how can i boot back into OS X or wipe my HD as I'm stuck?

MacBook Pro, OS X Yosemite (10.10.5)

Posted on Dec 26, 2015 3:40 AM

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Q: Unable to format partition

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  • by Eric Root,

    Eric Root Eric Root Dec 26, 2015 10:19 AM in response to thebeancounter13
    Level 9 (73,966 points)
    iTunes
    Dec 26, 2015 10:19 AM in response to thebeancounter13

    Would you make a screen shot so people can see what you are seeing? Make sure you cover any personal information using Preview. Post the screen shot in a Reply using the camera icon or you can drag the screen shot into a reply. Copy and paste doesn't work.

     

    Screen shots

  • by thebeancounter13,

    thebeancounter13 thebeancounter13 Dec 26, 2015 10:32 AM in response to Eric Root
    Level 1 (0 points)
    Dec 26, 2015 10:32 AM in response to Eric Root

    IMG_5867.JPGHI Eric,

     

    First of all thanks for taking the time to respond and attempt to help me, its much appreciated!

     

    Picture now attached. so as mentioned above my mac now boots into utility, if i go into disk utility i get the above screen - i.e. unable to erase. If i choose install OSX it only gives me the 600mb recovery drive to choose from, not the 250gb SSD?

     

    Thanks again

  • by thebeancounter13,

    thebeancounter13 thebeancounter13 Dec 27, 2015 1:50 PM in response to thebeancounter13
    Level 1 (0 points)
    Dec 27, 2015 1:50 PM in response to thebeancounter13

    to add further info to my issue...

     

    i installed a fresh copy of yosemite onto an external HD i had plugged in just via the standard os x utilities and it installed fine and is now running completely normal, HOWEVER , the internal HD is still not running properly and now just shows on disc utilities exactly as above....(i.e. no option to erase, and when i click on partition everything is greyed out).

     

    can anyone advise?

  • by MrHoffman,

    MrHoffman MrHoffman Dec 27, 2015 2:40 PM in response to thebeancounter13
    Level 6 (15,637 points)
    Mac OS X
    Dec 27, 2015 2:40 PM in response to thebeancounter13

    If all you want to do is completely erase and reformat the entire disk — deleting all files on all partitions on the selected target disk — build yourself a bootable installer, reboot holding the option key to select and then boot that, and reformat from there.

     

    As a precaution, disconnect all external devices except for the installer disk.  Don't have any of your backup disks connected when you're erasing or reformatting.

     

    If there's a fusion drive around, recreating that can be a bit more tricky.  AFAIK, fusion drives aren't very common on Mac laptops, though.

     

    Here's the image from earlier in the thread, rotated for easier viewing...

    IMG_5867.JPG

  • by thebeancounter13,

    thebeancounter13 thebeancounter13 Dec 27, 2015 2:47 PM in response to MrHoffman
    Level 1 (0 points)
    Dec 27, 2015 2:47 PM in response to MrHoffman

    hi mrhoffman,

     

    Thanks for the response and attempting to help!

     

    However I'm not sure you read my post above yours.

     

    I did just that. Installed OS X onto a external HD, booted from it and then attempted to wipe my built in HD but it still doesn't let me.....

     

    and thats the issue I'm having.

  • by MrHoffman,

    MrHoffman MrHoffman Dec 27, 2015 3:07 PM in response to thebeancounter13
    Level 6 (15,637 points)
    Mac OS X
    Dec 27, 2015 3:07 PM in response to thebeancounter13

    So /dev/disk1 is the external that you've booted from?  If that disk1 is your external minimal OS X boot disk, then your target volume may have been created as an encrypted core storage volume, and — if so — then see this discussion.  Maybe also this one.

  • by thebeancounter13,

    thebeancounter13 thebeancounter13 Jan 11, 2016 5:35 AM in response to MrHoffman
    Level 1 (0 points)
    Jan 11, 2016 5:35 AM in response to MrHoffman

    hi,

     

    i know this is an old thread but i fixed my problem so would like to close this off.

     

    After booting into an external OS X and then having my local HD showing in disk utilities, although i couldn't format from disc utilities i found a piece of code online that let me wipe it in terminal. This this brought it back into disc utility as it should do, a quick normal format, partition and then fresh install of OS X and all ok