# EFI Partition Recovery



## querycat (Apr 16, 2013)

Hi guys.
I did a stupid thing...
In the process of trying to shrink my Windows/Bootcamp partition and ultimately extend my mac partition, i deleted the EFI partition (200mb partition).

Now the macbook doesn't recognise that mac is installed and i can't boot to it.

Windows still works, i'm using it right now, but i need mac back ASAP.

*How do i go about recovering the EFI partition?*

Here are some details about my system:
13" Macbook Pro
Mountain Lion on Mac partition
Windows 7 on Bootcamp


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## sinclair_tm (Mar 11, 2005)

Did you create a bootable DVD or USB installer? If not you'll need to boot into the network recovery mode and see if the installer sees your volume. If not, you'll need to boot into Target Disk Mode and connect to another Mac and see if you can get your info off of it (If you don't have a backup.) because you'll need to reformat the drive (So back Windows up too!).


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## querycat (Apr 16, 2013)

sinclair_tm said:


> Did you create a bootable DVD or USB installer? If not you'll need to boot into the network recovery mode and see if the installer sees your volume. If not, you'll need to boot into Target Disk Mode and connect to another Mac and see if you can get your info off of it (If you don't have a backup.) because you'll need to reformat the drive (So back Windows up too!).


This sounds like very useful information, but unfortunately I'm a windows tech and don't know a huge amount of Mac troubleshooting. I don't suppose you'll be able to link me some walkthroughs on your suggested approach?

Edit: I read over your post a few times and it sounds like you're suggesting a backup and format is necessary. Is that right?


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## querycat (Apr 16, 2013)

I should probably note i can see the entire Mac HD from my bootcamp. I can also see the EFI partition (although it's now empty) in Windows' Disk Management. 

Is it possible for me to download what's necessary and somehow install it onto the partition?


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## sinclair_tm (Mar 11, 2005)

I don't believe you can download and install what you need, that information will be unique to the Mac in question. As for how to do what I said, Apple's support site has all that info with a quick search. Most times it's on the front page already. But yes, you're fastest and easiest solution will be to backup everything, and then wipe the drive and reformat it.

How are you trying to get back to the Mac partition? I'm surprised it's booting into Windows.

EDIT:

I started remembering something and checked online, the EFI partition isn't required to boot into OS X. It is a space for updating the firmware of the Mac. So it is normally blank. This goes back to how are you trying to get it to boot into OS X?


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## querycat (Apr 16, 2013)

sinclair_tm said:


> I don't believe you can download and install what you need, that information will be unique to the Mac in question. As for how to do what I said, Apple's support site has all that info with a quick search. Most times it's on the front page already. But yes, you're fastest and easiest solution will be to backup everything, and then wipe the drive and reformat it.
> 
> How are you trying to get back to the Mac partition? I'm surprised it's booting into Windows.
> 
> ...


Hi again,
I'm trying to boot into OSX by holding alt/option while it's starting up. Only Windows is visible. Like i said all my files are still on the Mac HD partition, so i find it odd that i can't boot into it

Thanks for your assistance


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## sinclair_tm (Mar 11, 2005)

When booted into Windows, open the Boot Camp control panel. Now select the OS X volume from there, and click reboot and see if it goes to OS X. You can also try holding down the X key when you turn it on and see if it goes to OS X.


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## querycat (Apr 16, 2013)

i tried both of the suggestions and both of them just reverted to boot windows :/

i was so hopeful they'd work :'(


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## sinclair_tm (Mar 11, 2005)

Look on Apple's support website to see how to network boot your Mac. Once it's booted into the OS installer, select your language, and then you should get a menu bar at the top. Select Startup disk under Utilities and see if the Mac OS shows up there. If it does, select it then hit restart. If it doesn't, close that window and select Disk Utility from the Utility menu. Now select the OS X partition and do a repair. Keep repairing it until it no longer fixes anything. Now quit Disk Utility and try Startup Disk again. If it still doesn't show up, you can try doing a repair of the OS X system from the installer. If a repair doesn't work, you can install the OS and keep user files. It'll move the old OS to a different folder.

Just make sure you have everything on the hard drive backed up as you may damage both OS X and Windows and have to just wipe and reinstall.


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## MartyF81 (Jan 23, 2013)

I am wondering if the OS-X partition is even there? Shouldn't it show up when holding Option during boot?


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## sinclair_tm (Mar 11, 2005)

Only if the system is "Blessed". Being that he can see it from Windows shows that it is still there. The issue is either part of the OS got corrupted, or the OS got "unblessed".


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## querycat (Apr 16, 2013)

honestly i don't understand this netboot stuff. it looks like i need another mac running as a server so i can install off it, but i don't have another mac so i can't do that.
I can make a DVD to boot from but as far as i can tell I'd need to go and get a dual layer DVD.
Is it possible to use a USB stick instead?


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## querycat (Apr 16, 2013)

I just tried the Command+R boot to repair the boot, but i got the error code 2101f.
This macbook really doesn't like me anymore...


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## sinclair_tm (Mar 11, 2005)

Try command+option+R (I think that's it.) for the netboot. This will not boot from a local server, but from Apple's servers.
You can boot from a USB stick, but it'll require another Mac since you'll need to download the installer from the Mac App Store, and then create the bootable installer in the USB stick. Do you have a local Apple store that you can take it in to?


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## querycat (Apr 16, 2013)

sinclair_tm said:


> Try command+option+R (I think that's it.) for the netboot. This will not boot from a local server, but from Apple's servers.
> You can boot from a USB stick, but it'll require another Mac since you'll need to download the installer from the Mac App Store, and then create the bootable installer in the USB stick. Do you have a local Apple store that you can take it in to?


I think i have an iso of mountain lion sitting around somewhere in my backups so i'll hopefully be able to use that instead.
I'll give the netboot (using apple servers this time) a shot and see how i go 

Thanks!


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## querycat (Apr 16, 2013)

I attempted with some success, but mostly failure. It answers some questions though!

Here's a picture i took of the diskutility screen:
http://db.tt/bk3BXk6H 

As you can see the Mac HD partition is greyed out and is named: disk0s2
This is something i'm unfamiliar with but very brief research suggests it's a common issue. 

Obviously diskutility wasn't able to repair the partition, so i will probably have to go ahead and reformat and reinstall.
You can see where the other 2 partitions are that i was trying to merge to add to the Mac HD, but i never got round to doing it before the Mac partition became corrupt. 

Any ideas why this has happened?


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## sinclair_tm (Mar 11, 2005)

That's not the Mac volume. It's formatted ExFAT, which isn't compatible with OS X. OS X must be on a Mac OS Extended (HFS+) volume to boot. I'm not sure how the format got changed, yet you can still see the info, but yes, you need to reformat the whole drive and start over. You also can't add to the beginning of the OS X volume (Add New Volume to it.), only to the end. And the volume New can't be added to the Mac volume either.


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## querycat (Apr 16, 2013)

sinclair_tm said:


> That's not the Mac volume. It's formatted ExFAT, which isn't compatible with OS X. OS X must be on a Mac OS Extended (HFS+) volume to boot. I'm not sure how the format got changed, yet you can still see the info, but yes, you need to reformat the whole drive and start over. You also can't add to the beginning of the OS X volume (Add New Volume to it.), only to the end. And the volume New can't be added to the Mac volume either.


Thanks again for your assistance. It's much appreciated.

I ended up borrowing an 8gb flash drive and just starting from scratch. I think it's probably the best outcome as i've been able to work from a clean installation of snow leopard, which has sped some things up as well.
I wasn't aware, but i was also able to simply copy the apps from my backup into OSX and they ran seamlessly without requiring any reinstallation!

So, the issue is essentially solved :thumb:

Thanks!


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## alexbrown (Sep 17, 2013)

If you formatted/deleted windows partition then it may be possible to recover that partition but its doubtful that you may recover all the files/data on it.


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## sinclair_tm (Mar 11, 2005)

Don't post in old threads please.


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