Prohibitory symbol fix

shane0524

macrumors newbie
Original poster
Jun 23, 2019
9
0
Have a 2014 5k 27" iMac, upon boot I receive the prohibitory symbol and it will not start the OS. It seems that it will not mount the Macintosh HD partition. Also will not repair thru disk utility. Strangely my windows 7 bootcamp partition starts and runs fine.


have it in target disk mode now and it just will not mount the mac partition. Drive seems to be on its way out or the mac partition has some issues. Big problem is that I have no back up of this machine and I would really like to get this data with out taking it to some data recovery place, anyone know a way?


PS preliminary genius bar diagnostics show drive is O.K.
 

Honza1

macrumors 6502
Nov 30, 2013
413
137
US
...Big problem is that I have no back up of this machine and I would really like to get this data with out taking it to some data recovery place, anyone know a way? ...
This is the crazy thing you see here again and again. No backup. Drives are really cheap now, your data are really valuable and important. Time Machine is free and Carbon Copy Cloner (or Disk duplicator) are quite cheap. Drives (any drives, all drives, every drive eventually) do fail. OSX or Windows or Linux...

Now it is a challenge with no guaranteed solution:

I would extract the drive and put that in (USB) external enclosure/dock. I would try to mount it to another Mac and see, if I can get the data this way. This gives you all the tools system gives you - DiskUtility mainly.

BUT before you do that:

Be vary careful on trying to fix that disk, it may fix it - or destroy it altogether. So my first step would be to create bit-to-bit clone = get same size empty disk and clone using disk duplicator the disk there - there are duplicators, which copy raw disk data - sector by sector or whatever that is called today. This makes exact copy of the disk, even if the disk does not mount due to disk structure errors etc. Easiest are hardware dual docks/duplicators which can do this, I also had used once linux command line app (forgot its name) with two usb docks. That was more capable as it could try to read sector multiple times, so it succeeded on damaged drive hardware duplicator failed...

Then I would try to repair original - or the copy they are the same now - disk structure.

Now, that requires a lot of other hardware - another Mac, disk duplicator, usb dock(s), and some spare drives. Takes time... Success is not guaranteed.

Backup would have been cheaper and faster.
 

Fishrrman

macrumors P6
Feb 20, 2009
17,160
5,521
You don't have to take the drive out.

Here's what I'd suggest.
You'll need an EXTERNAL USB drive of some kind. It should be large enough to hold the contents of your Mac partition.

Then, do this:
1. Power down (all the way off) and connect the external drive.
2. Press the power on button and IMMEDIATELY hold down "command-OPTION-R" to boot into INTERNET recovery (NOT "the recovery partition)
3. You'll see the "internet symbol" and if you're connected via wifi you'll probably have to enter your wifi password.
4. When you get to the utilities menu, if the OS installer is open, quit it.
5. Open Disk Utility and ERASE the EXTERNAL drive to Mac OS extended with journaling enabled, GUID partition format.
6. When done, close Disk Utility and re-open the OS installer.
7. The installer will offer to show you ALL connected drives. POINT IT at the EXTERNAL drive
8. Now, choose to install a clean copy of the OS onto the EXTERNAL drive. The Mac may reboot once or twice, and the process will take some time. BE PATIENT.
9. When done, you should see an "initial setup screen" for the new install on the external drive. So... go ahead and "set it up" with a username and password.
10. I'm not sure if these next steps will work, you're going to have to try it.
11. As you go through setup, when you get to the part where setup assistant asks if you want to import data from another drive, YES, you want to do this.
12. Does setup assistant "see" the Mac partition on the internal drive (even if you couldn't "boot from it")?
13. If it does, leave EVERYTHING checked and go ahead and see if setup assistant can "import" the contents of the Mac partition of the internal drive.

OK... does this work?
If so, you have now recovered your personal data and apps to the EXTERNAL drive.
From this point, you can begin work on getting the internal drive "back into shape".

Even if setup assistant can't migrate the data, YOU'LL STILL HAVE A BOOTABLE MAC DRIVE from which to boot the iMac.

My best advice:
DO NOT USE Bootcamp in the future.
Use either an emulated solution (VMWare fusion or Parallels)... or...
Get a cheap PC and use that instead.
 
Last edited:

shane0524

macrumors newbie
Original poster
Jun 23, 2019
9
0
This is the crazy thing you see here again and again. No backup. Drives are really cheap now, your data are really valuable and important. Time Machine is free and Carbon Copy Cloner (or Disk duplicator) are quite cheap. Drives (any drives, all drives, every drive eventually) do fail. OSX or Windows or Linux...

Now it is a challenge with no guaranteed solution:

I would extract the drive and put that in (USB) external enclosure/dock. I would try to mount it to another Mac and see, if I can get the data this way. This gives you all the tools system gives you - DiskUtility mainly.

BUT before you do that:

Be vary careful on trying to fix that disk, it may fix it - or destroy it altogether. So my first step would be to create bit-to-bit clone = get same size empty disk and clone using disk duplicator the disk there - there are duplicators, which copy raw disk data - sector by sector or whatever that is called today. This makes exact copy of the disk, even if the disk does not mount due to disk structure errors etc. Easiest are hardware dual docks/duplicators which can do this, I also had used once linux command line app (forgot its name) with two usb docks. That was more capable as it could try to read sector multiple times, so it succeeded on damaged drive hardware duplicator failed...

Then I would try to repair original - or the copy they are the same now - disk structure.

Now, that requires a lot of other hardware - another Mac, disk duplicator, usb dock(s), and some spare drives. Takes time... Success is not guaranteed.

Backup would have been cheaper and faster.
Trust me i understand the importance of backups, but this is a family machine and it just does not have one so we work with what we have in front of us,

anyways, is connecting to this machine with target disk mode not the same as having the disk removed from the machine and connected seperatly?
 

shane0524

macrumors newbie
Original poster
Jun 23, 2019
9
0
You don't have to take the drive out.

Here's what I'd suggest.
You'll need an EXTERNAL USB drive of some kind. It should be large enough to hold the contents of your Mac partition.

Then, do this:
1. Power down (all the way off) and connect the external drive.
2. Press the power on button and IMMEDIATELY hold down "command-OPTION-R" to boot into INTERNET recovery (NOT "the recovery partition)
3. You'll see the "internet symbol" and if you're connected via wifi you'll probably have to enter your wifi password.
4. When you get to the utilities menu, if the OS installer is open, quit it.
5. Open Disk Utility and ERASE the EXTERNAL drive to Mac OS extended with journaling enabled, GUID partition format.
6. When done, close Disk Utility and re-open the OS installer.
7. The installer will offer to show you ALL connected drives. POINT IT at the EXTERNAL drive
8. Now, choose to install a clean copy of the OS onto the EXTERNAL drive. The Mac may reboot once or twice, and the process will take some time. BE PATIENT.
9. When done, you should see an "initial setup screen" for the new install on the external drive. So... go ahead and "set it up" with a username and password.
10. I'm not sure if these next steps will work, you're going to have to try it.
11. As you go through setup, when you get to the part where setup assistant asks if you want to import data from another drive, YES, you want to do this.
12. Does setup assistant "see" the Mac partition on the internal drive (even if you couldn't "boot from it")?
13. If it does, leave EVERYTHING checked and go ahead and see if setup assistant can "import" the contents of the Mac partition of the internal drive.

OK... does this work?
If so, you have now recovered your personal data and apps to the EXTERNAL drive.
From this point, you can begin work on getting the internal drive "back into shape".

Even if setup assistant can't migrate the data, YOU'LL STILL HAVE A BOOTABLE MAC DRIVE from which to boot the iMac.

My best advice:
DO NOT USE Bootcamp in the future.
Use either an emulated solution (VMWare fusion or Parallels)... or...
Get a cheap PC and use that instead.
I just created a bootable drive with an external HDD and it does not seem to be recognizing the drive to transfer the old data during setup
 

Honza1

macrumors 6502
Nov 30, 2013
413
137
US
Trust me i understand the importance of backups, but this is a family machine and it just does not have one so we work with what we have in front of us,

anyways, is connecting to this machine with target disk mode not the same as having the disk removed from the machine and connected seperatly?
If target disk works, more or less yes. If it does not, extracting disk and placing into usb enclosure/dock will replace all other hardware and give you more options. From your subsequent post I suspect you may need every option there is :-(

I kind of like to isolate the problem as much as possible. That way the only thing from the non-functioning system left is the drive. Everything else is different, likely tested and in working condition. Would hate to troubleshoot drive and it turned out to be cable or some other iMac component.
 

Fishrrman

macrumors P6
Feb 20, 2009
17,160
5,521
shane wrote:
"I just created a bootable drive with an external HDD and it does not seem to be recognizing the drive to transfer the old data during setup"

OK, but at this point, you're saying that you CAN now boot up the iMac?
Using the external boot drive?
That's an important first step.

I don't want to insult you with this next question:
Have you done this:
a. Click on the desktop to make the finder active
b. Go to finder --> preferences --> general
c. Put a checkmark in the "hard disks" and "external disks" boxes
????
 
Last edited: