Friday, February 8th, 2008 at 10:19 PM
If you’ve formatted a bootable hard drive on an Intel Mac (or have perhaps been tinkering with the wholly unsupported Leopard OSx86…) and later decided to put the drive to use under Windows XP, you might find that you’re unable to format the disk, with Windows Disk Management claiming the device is a “GPT Protective Partition.” You can’t format it, partition it, or even assign it drive letter. What gives?
The secret is that the GPT scheme protects itself from being read and possibly erased by utilities or operating systems which aren’t able to correctly interpret it. Until just recently, I wasn’t aware that a filesystem even had such a capability. I was under the false assumption that a utility running externally of the drive in question could always format a detected disk, no matter the filesystem in place. I doubt it could withstand the raw formatting power of DBAN, but it was enough to befuddle Windows XP.
How can the GPT scheme be undone? Typically, software that can create it can also destroy it. In my case, Leopard’s Disk Utility application was able re-partition the drive as follows:
- Boot a Leopard DVD (retail or OSx86) and choose your native language at the first screen.
- Run “Disk Utility” from the “Utilities” menu and highlight the offending drive on the left.
- Navigate to the “Partition” tab, choose “1 Partition” from the Volume Scheme popup menu, select your new desired format (or “Free Space”), and make sure to click the “Options…” button
- From the “Options” screen, you can choose between GUID Partition Table, Apple Partition Map (for PowerPC Macs), and Master Boot Record. Choose MBR, and click OK.
- Click “Apply” to partition the drive using the more common MBR scheme, and thus completely erase all trace of the GPT partition.
Once the partitioning is complete, you’ll be able to format and use the drive under Windows XP, Mac OS 9, or any other system incapable of comprehending GPT Partitions.
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Or if you prefer, Linux boot CD to the rescue. Boot up, and at the prompt:
dd if=/dev/zero of=/dev/[DRIVE_DEVICE_HERE] bs=1k count=2
That will zero out the first 2KB of the drive. After that, any tool will see it as completely unformatted, and you can do what you like with it.
Replace [DRIVE_DEVICE_HERE] with the appropriate Linux device node for the drive you want to erase. SATA drives are sda, sdb, sdc, etc. depending on which port they’re plugged into. PATA’s go hda, hdb for primary master/slave; hdc hdd for secondary master/slave.
Or use the ‘DiskPart’ tool on the XP command line:
use ‘list disk’ to find the volume number of the GPT volume, then use ’select’ to focus on it
then use the ‘clean’ function and then exit the tool
***WARNING*** ALL DATA WILL BE LOST ***WARNING***
now you can create a new partion and format it.
DiskPart in cmd worked a treat for me, thanks Fly! Lots of long frustrated hours have finally come to a winning conclusion! ^_^
A drive I was using with FreeNas was also showing itself as GPT. The comment made by Fly enabled me to format the driver under Windows XP. Great!!
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Wow, you guys just saved me from pulling my hair out. I bought a drive off of a friend and have been very frustrated with the whole GPT Protection Partitions thing!
My friend neglected to mention that the drive used to be inside of one of his Macs…
I just want to say thank you to Fly for the “DISKPART” solution it worked great now I can finally use my usb hard drive.
THe all thing drove me crazy before.
Thank you Fly
Thanks for the Diskpart solution to the otherwise GPT locked partition !
Diskpart worked, cheers.
Thanks, DISKPART – LIST DISK – SELECT – CLEAN – worked great.
Techsas
It worked AWESOME for me thanks,
Type :
DISKPART
get the disk ID with
LIST
select the disk to fix with
SELECT DISK number
then type
CLEAN
I couldn’t partition with windows tool right afterward so I went with (still in diskpart)
CREATE PARTITION
PRIMARY
then just use windows to format :)
diskpart in cmd saved me.
Thx a lot
if that is the case, can we possibly retrieve the data after undoning the GPT Protective Partitions?
This site came up first in a Google search. The Diskpart suggestion worked perfectly for me.
Thanks and it works!
Hey, that DISKPART option worked like a charm!
Now I can use my drive as a MBR, which is why I’ve been suffering due to protective partitions.
THANK YOU FLY!
Fly – that just saved me a lot of hassle bud. You are the man!
Seriously, the DiskPart solution just eliminated alot of hassle for me!
DiskPart worked great for me, just follow comment #11 and your good to go!
thanks for this trick,
that saved me alot of time.
hey thanks a lot it really helped. only reason I noticed this was because I went to plugin my HDD to my windows computer and it wouldn’t mount. I don’t understand the point of this as you can open the GPT drives using linux and could read and write. glad I caught it early enough where I could put it on my other hard drive as it is a 1TB drive.
Did not work for me with USB flash drive.
freenas formatted gpt-ufs external drive. Had a network worm access drive and delete all mp3, docs and pdfs.
Only recovery utility able to get it back was UFS File Explorer 3.9.
And using diskpart command to format it back to ntfs after recovery transfer.
Same problem and I confirm
Great work with diskpart.
Thank
THANK YOU SO MUCH FLY!!!
GREAT TUTORIAL!!
Good job, very clear
Thanks
Great information thanks for helping a complete novice, I got there in the end.Thanks one and all.
Thanks for the DISKPART advice, worked a treat!
diskpart for the win! thanks a million!
This worked awesome with reformating a disk previously formated with Windows 7 too…
It worked AWESOME for me thanks,
Type :
DISKPART
get the disk ID with
LIST
select the disk to fix with
SELECT DISK number
then type
CLEAN
I couldn’t partition with windows tool right afterward so I went with (still in diskpart)
CREATE PARTITION
PRIMARY
then just use windows to format :)
You will not even need to create the partition within Diskpart, just ‘clean’ and exit.
Then open Windows Disk Management; You will see the cleaned disk as “Offline”. Right click on it´s left-most header on the lower part of Disk management (where size etc. is shown), select “Initialize” – and you are free to partition and format it as required!
Just did that myself.
Thanks. Thanks for the DiskPart tip, worked like a charm!
Awesome, DiskPart was the winner and resolved the gpt protective problem. Thanks for this helpful tip.
thank you.
I formated my disk with Windows 7. And only it coud open the disk. Now thank’s to the diskpart I can use it in every computer.
Awesome.
Thanx man , great work ! :)
thanks a lot for the instructions on the diskpart tool. Saved me a TON of time :-)
Yup.
Diskpart was a much quicker method that jacking this external into a mac.
Thanks, Fly.
DiskPart worked like a charm. Thanks!
DiskPart worked great!! Thanks
Don’t know who you are fly… but ur def a superfly ;) thanks a mil for the tip! My friend been pi**ed off for a few weeks now about not have his 2 drives working, so last few days i’ve been trying to sort it out and now i checked internet sites and this best way, so simple and quick to complete to. much appreciated!!
Thanks for the post, good info.
Just used the diskpart tool myself, and it worked great :-)
my drive came off of a windows vista but with the above help . its working now, just lost all the data.
Hello. I had disk formatted MacOs 10.6. I could not formatted under windows.thanks a lot for the instructions. It is work fine.
Diskpart worked for me. thanks so much
Tried with diskmgmt.msc or with regedit HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices but did not work.
With diskpart it is solved. Thanks