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What will happen if I remove Apples EFI partition?

Posted on 2014-12-18
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Last Modified: 2016-06-07
I want to completely remove the EFI partition on my new Mac Book Pro.

Already know that " FileVault "  will not work, but never use FileVault so do not care.
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Question by:SuperSenile
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by:Seth Simmons
Seth Simmons earned 83 total points
ID: 40507408
not a mac person myself, but generally speaking if you boot UEFI and remove the EFI partition, the system won't boot since it needs that partition
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Eoin OSullivan earned 251 total points
ID: 40507484
Don't remove the EFI partition .. especially from the main HD of a MacBook.  You really have to either remove the HD from the device or boot from an external source to be able to do anything like that and you REALLY need to know what you're doing.

Even when you remove it you cannot easily merge the partition into the rest of the HD without wiping and reformatting the entire HD.

Basically leave it alone.
OSX looks for and uses that partition to manage booting, to enable OSX install/upgrades when installing or restoring via iCloud etc and it is not worth the small space saving for all the work required to recover it.  Disk Utility does not even show these system partitions by default for security reasons.
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by:SuperSenile
ID: 40507618
Wow - That was fast.

Thanks to both eoinosullivan  and  Seth Simmons.

I slapped myself several times to keep myself from deleting the EFI partition.   ;-)


Previously I played the part of Black Hat Bad Guy  and deliberately deleted the EFI partition.

NONE of my Backup Schemes would re-create that partition - - - Not Time Machine - - - not Carbon Copy Cloner - - - I have not tried "Clone X" yet which supposedly will re-create ALL the partitions on my main one-TB internal drive.

I am a bit hesitant about trying "Clone X" because I can't find any reviews about their product.

Solid State Drives are particularly difficult to exactly clone, because of wear-leveling and trim.

My old standby terminal   "dd"  will not work with Solid State Drives,  GRR


What good are backups if any Bad Guy Hacker can defeat them by messing up my EFI partition ???

Just grumbling, sorry about that.
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by:Eoin OSullivan
ID: 40507761
If the main HD partition is backed up then deleting the EFI is a nuisance but doesn't compromise your real data. Normal OS X users are unlikely to know the EFI exists or how to delete it as it is hidden by default in disk utility application. If a hacker has access level to Mac computer then deleting the EFI is the least of your worries!!
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by:SuperSenile
ID: 40508146
..." nuisance but doesn't compromise your real data "

True enough, however the only way I know how to " get back "  my EFI partition involves at least a 5-hour download from Apple's server - - - in times that has been a 10-hour download.

That tends to lose my clients.  :-(

I tried and tried to educate myself enough to manually rebuild the partition myself, but it is a slow process, because of Apple's use of "hard links"  etc.

I would not be able to manually replace what is INSIDE the partition of course.  I hope that "Carbon Copy Cloner" will be able to replace the code inside the partition - - - they advertise that they can.

http://www.macissues.com/2014/08/27/how-to-hide-a-hard-drive-partition-on-your-mac/

...appeared to be my salvation, but for some reason my command to  "save"  (namely control-O )   and my command to exit the pico editor do not work - - - those commands also do not work on the "nano" editor that replaces the "pico" editor.

Bottom line, do not get senile like me.    ;-)
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by:noxcho
noxcho earned 83 total points
ID: 40508718
The fact is that Carbon and other backup tools are taking backup of data and not the HDD entirely or a partition. That's why they do not catch the image of EFI partition as well.
EFI partition is a service partition for a GPT drive which is standard format for MacOSX boot drive. If you remove it - then your system won't boot.
How to backup it and other partitions completely:
Get a copy of Hard Disk Manager from Paragon and perform the backup from a Boot CD which comes with this tool. It will backup entire drive including EFI partition and all the data.
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by:Eoin OSullivan
ID: 40508762
nano on OSX is just pico slightly modified.

To Save .. press Ctrl+O (sometime you need to press it twice) and you should see the filename and path info appear at the foot of the terminal window .. asking if you want to SAVE .. press ENTER to accept

Some key tools like Typinator .. will interfere with some key combinations in Terminal .. and you might have to disable them or change the keymappings (you can do this for nano if you use it a lot and some key combinations are causing errors).
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by:serialband
serialband earned 83 total points
ID: 40508912
If you're working on Macs on a regular basis, you should create OSX installer USBs, then you don't have to download the copy each time.  I keep all the installers around, so that I'll have them, even if the internet is down or very slow.  I have Lion through Mavericks saved.  I currently have Yosemite on USB and the rest on disk in case I need it.  Making a bootable USB takes 7-20 minutes, depending on the laptop I use.  It's faster from an newer SSD.  Snow Leopard and prior are still on DVDs for the old systems that need them.  You should also have a thunderbolt cable for speedy data transfers.

You could try to install the same version of OSX onto the new drive to create the EFI and recovery partition first.  Then, rsync the enitre /Applications/ and /Users/ folder.  It should be faster than dd.  rsync won't work for some licensed products like Office 2011.

You can also just use the Migration Assistant to pull all the relevant User Data and Application over from the other Disk.  The thunderbolt cable helps speed migrations between computers..  If you have Filevault enabled, you pretty much have to do it this way.

You can also use Disk Utility to do the Disk Cloning process.  I believe Carbon Copy Cloner uses Disk Utility to do the cloning.  You can use the App or do this on the command line.

I haven't used dd for OSX recently, certainly not for SSDs yet, but are you sure dd isn't working to copy the EFI?  If you run diskutil list, you should see the EFI on one of the slices, normally /dev/disk0s1.  Are you copying the entire disk (/dev/disk0) or were you copying just the slices (/dev/disk0s4)

If you're working on osx(unix in general), you should eventually learn vi (better for remote connections, especially over modem) and/or emacs editors.  nano/pico are poor substitutes that beginners use on the command line, because they're initially easier to use.
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Author Comment

by:SuperSenile
ID: 40509029
" How to backup it and other partitions completely:
Get a copy of Hard Disk Manager from Paragon and perform the backup from a Boot CD which comes with this tool. It will backup entire drive including EFI partition and all the data. "

Thanks noxcho  for that info' - - - I will try it.    Supposedly " Clone X "  from a French company advertises that their software will do the same thing but users say that Clone X will actually do less than CCC.   ( Carbon Copy Cloner )

All you Experts Exchange people are certainly helpful.   I have battled this for months, dumping all sorts of senile power upon it with no results.

Thanks again to " eoinosullivan "  for that tip about pressing Ctrl+O twice sometimes when using the "nano" editor in Apple's Terminal utility, I will try that.

I also could not terminate the nano editor be pressing  Ctrl+X  so will try twice and maybe get lucky escaping from nano's clutches.



Thanks serialband for all your helpful comments such as:

" I haven't used dd for OSX recently, certainly not for SSDs yet, but are you sure dd isn't working to copy the EFI? "

serialband  I also have not used dd lately because I ran into all sorts of problems with dd when Apple switched to SSD on their entire line of computers, even the  " Mac Pro " .

No more spinning mechanical drives on that big expensive model, only SSD.

dd used to be my answer to copying entire drives, even whatever was in " free space ".

dd is still good for mechanical drives, but mechanical drives are getting as scarce as hen's teeth, as far as Apple is concerned.

SSDs are so radically different than spinning mechanical drives that apparently dd is useless for trying to backup / restore any SSD.

At least that was my impression, your milage may vary.
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