Can't Boot BootCamp After Resize!

Apple's Windows support uses an EFI CSM to "emulate" BIOS, which requires an MBR partition scheme. So Apple creates a hybrid MBR/GPT partition scheme in order to support Windows. Gparted depends on parted, which upon resizing a volume, rewrites the GPT and obliterates the MBR.

The CSM-BIOS thus can't find a valid MBR partition to boot from.

So what you need to do is download GPT fdisk (also known as gdisk) off SourceForge. It's a command line only application. You will need to learn how to use gdisk is interactive mode, go to the recovery menu, create a new hybrid MBR, add the Windows partition to the MBR, and set its boot flag, write out the new partition. Now you'll be able to boot Windows.

Before you begin, if you want, you can go to Terminal and type this command


This is a read only command and will display information on the MBR and GPT on the disk. Post that. Please highlight the pasted result in the forum entry window and use the # button in advanced editing to add code tags so the result formats legibly.

mfvisuals said:

I've also installed GPT fdisk onto my Mac. It says it includes something called "fixparts" which, based on the description, sounds like it might fix my issue.

Click to expand...

No fixparts is going to make repairs on the GPT, and the problem is not with the GPT on your drive. The problem is the MBR only contains a single entry that basically says "this is a GPT disk only" and the CSM-BIOS doesn't know how to deal with that.

So first you're going to make backups of all important data, just in case. Then you're going to run gdisk in interactive mode:
? gets you a list of commands
r will take you to the recovery menu
? lists recovery commands
h to create a new hybrid MBR

If you want to do it Apple's way, you can enter 2 3 4 to add all of your partitions to the MBR. Gdisk will then ask for each of those partitions if you want to accept the default partition type, which you do by just hitting return, and if you want to set the boot flag for that partition. You do not want the boot flag set for partitions 2 and 3, just for 4 - the Windows partition.

When done, you'll use the w command to write the new partition maps to disk.

So now I bet it either works, or you get a totally different error. We'll cross the totally different error bridge if you get to it.

mfvisuals said:

Not sure if this is related, but I just noticed that my Recovery HD partition (although still bootable) is now showing up in my Finder window... is there a way to hide that again?

Click to expand...

Weird. What are the results from:

Can I repair that using Windows Install DVD?

Click to expand...

Yes. You'll get an option to "Repair your computer" and then a System Recovery Options where you choose Startup Repair. That will replace the boot loaders on the disk. Likely the one in the first 440 bytes of the MBR is either toast or pointing to the wrong location. This should fix it.

----------

Please post the results for those two commands. They are read only commands and do not modify anything.

mfvisuals said:

Ok, so that resized the partition,

Click to expand...

No it did not. "diskutil resizevolume disk0s2 limits" only reports back the minimum and maximum resizing possible.

I'm going to attempt to repair the disk again via Disk Utility in Recovery HD. I also read somewhere that defragging the drive can help...

Click to expand...

This is why I find native booting of Windows to be irritating. VM is so much easier.

First of all, sorry for getting this old thread up. I've got here through intense google search as I searched for a solution to get my windows partition to work again.

I had a pretty similar problem resizing my OS X partition, to add a new ntfs partition for use with Windows. Now I ended up not being able to boot Windows anymore, then I tried the way murphychris recommended and voilá I could boot Windows again, but.. not entirely - it was in an endless circle in the bootup screen of Windows.

The next thing I've tried was to delete the new partition I made and let it be as it was before, but I guess I messed something up and I don't know how to explain it (english isn't my native language) but here is what I ended up with now:




The 132GB sized "disk0s3" should be my Windows 7 partition formated in ntfs. Is there some way to rescue it? There are some important files of mine and stupid as I am, I didn't make a backup before all of this, because of the lack of an external harddrive.

I really hope someone here can help me with the mess I made :x

@selladore

Post the results of

@selladore

The MBR and GPT are the same, so that's good. The problem is the partitiontypeGUID for partition 3 is incorrect, it's all F's, and when you created the hybrid MBR most recently it also inherited the FFs from the GPT.

So you need to change the partition type code for the 3rd partition, using gdisk, to 0700. And then create a new hybrid MBR just as you have before, and by default it'll get the right type code also.

I am having a similar problem to this. So when I first created my windows partition I allocated 50GB for it. Later I realized I needed more space so I shrunk my mac partition and used a third party tool to increase my windows partition without erasing and reinstalling windows. So what happened then is I recently decided to upgrade to Mavricks and that completely removed my windows partition at boot. The partition is there but it doesn't appear at boot and disk utility doesn't recognize it. So using the command you said to you this is what I got:
gpt show: /dev/rdisk0: mediasize=500107862016; sectorsize=512; blocks=976773168
gpt show: /dev/rdisk0: Suspicious MBR at sector 0
gpt show: /dev/rdisk0: Pri GPT at sector 1
gpt show: /dev/rdisk0: Sec GPT at sector 976773167
start size index contents
0 1 MBR
1 1 Pri GPT header
2 32 Pri GPT table
34 6
40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
409640 776880976 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC
777290616 199482519
976773135 32 Sec GPT table
976773167 1 Sec GPT header

----------


The above information is produced using sudo gpt -r -vv show /dev/rdisk0


Below are the contents produced using fdisk
Disk: /dev/disk0 geometry: 60801/255/63 [976773168 sectors]
Signature: 0xAA55
Starting Ending
#: id cyl hd sec - cyl hd sec [ start - size]
------------------------------------------------------------------------
1: EE 1023 254 63 - 1023 254 63 [ 1 - 409639] <Unknown ID>
2: AF 1023 254 63 - 1023 254 63 [ 409640 - 776880976] HFS+
3: EE 1023 254 63 - 1023 254 63 [ 777290616 - 199482552] <Unknown ID>
4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

@o2themar

No you have a different problem. Everyone else had four partitions, you have two. You're actually missing the Windows partition entirely as well as Recovery HD. But it's likely due to the same reasons as this problem.

Provide the result from


----------

murphychris said:

@o2themar

No you have a different problem. Everyone else had four partitions, you have two. You're actually missing the Windows partition entirely as well as Recovery HD. But it's likely due to the same reasons as this problem.

Provide the result from

Code:

sudo fdisk /dev/rdisk0

Click to expand...

Ahh OK it got posted after I already replied.

So the MBR has 3 partitions, compared to the GPT which has 2. The MBR 3rd partition is 0xEE and there should only be one of those, so I don't know how you ended up with that, and therefore I have no idea how to help you fix this problem other than to suggest the link above, which in turn mentions a 52 page thread on Apple's forums. You can start on page 48 to work on the testdisk stuff and see if you can find the true start of the Windows partition. It will have a start sector after 777290616, maybe 777291776 since that's the closest 1MB aligned value.

Since everyone else has a Recovery HD and you don't, instead of deleting and then creating a new 4th partition, you have nothing to delete and you'll create a 3rd partition with the information you find from testdisk. When it comes time to make the hybrid MBR with gdisk, you'll only add partitions 2 3 rather than 2 3 4. Enter them just like that, with only space between.

@murphychris

I don't even understand what I just did, but you saved my ass! Thanks.

Just out of curiosity, as now I'm back from where I've started - is there some "secure" way of splitting my OS X partition into two, while the new one gets a ntfs formated "D:" partition, I could use with windows?

Or alternatively: Could I use Paragon HFS+ to use my OS X partition just as a second partition to Windows or are there some restrictions?

So @murphychris
I would like to turn your attention to the results I got from testdisk. As you can see from the image that highlighted MS data is the one I want. It has the 101GB that I allocated for my windows partition. If this is correct how can I fix the partition table using this.

selladore said:

Just out of curiosity, as now I'm back from where I've started - is there some "secure" way of splitting my OS X partition into two, while the new one gets a ntfs formated "D:" partition, I could use with windows?

Click to expand...

The nearly secure way of anything is multiple backups with a tested restore method, so that your penalty for an irreversible mistake is near zero. And I also haven't tested this, but it should be possible in your case because you're in the unique situation without a Recovery HD partition taking up one of only 4 slots in the MBR.

But the other question what's the point of separate partitions on the same disk? It tends to just increase seek times.

It's an open question how to do it though. I'd use diskutil resizevolume <device> limits to see the min-max sizes available. If the OS X volume is highly fragmented or full you won't be able to shrink it by much anyway.

And then you either need to take a blind leap of faith doing this with Disk Utility. Or diskutil resizevolume. And just check both MBR and GPT after each step to make sure things aren't getting out of sync. And for sure have current backups.

----------

@o2themar

Press P to list files. Make sure it doesn't say the filesystem is damaged/corrupt and you can actually navigate folders/files. You can even extract files at this point so you might consider doing that if there's something important you want.

Make a new window so you can keep the testdisk one up. And you'll need to use gdisk to create a new partition using the Start and End values from testdisk, when gdisk asks for First and Last sector values for the new partition. And use partition type code 0700. And then w to write out the change to disk. Reboot.

At this point you should have read only access of the Windows volume from the OS X Finder. Another opportunity to get at your files.

Next, you'll go back to gdisk and create a new hybrid MBR, adding, in your case, partitions 2 3, say yes to putting the EFI GPT in the first MBR entry, accept the default values for type/hex codes by just hitting return when asked, and don't make partition 2 bootable, but do make 3 bootable.

Ok so I am able to retrieve files from using the p command on that volume. So you said to first create a new partition using the start and end values from testdisk using gdisk. Do I use the o command to create a new empty GUID partition table (GPT) or do I use the n command to add a new partition? Also ,even though I am not at that part yet, when I have read access in Windows would I do the second part in Windows or OSX?

o2themar said:

Do I use the o command to create a new empty GUID partition table (GPT) or do I use the n command to add a new partition?

Click to expand...

New partition. NOT new partition table! If you make a new partition table you'll nuke all of your data on the disk.

Also ,even though I am not at that part yet, when I have read access in Windows would I do the second part in Windows or OSX?

Click to expand...

You will NOT have read access in Windows. You will have read-only access when rebooting OS X, in the Finder. And the 2nd part, to create the new hybrid MBR is done in OS X also in gdisk in its recovery menu.


-------

OK actually, since you posted your GPT to this forum, if you were to accidentally create a whole new GPT, while you would lose access to all of your data, it is recoverable. The partition table is not stored in the same location as your data so the data is completely intact.

Ok so after doing the first part this is what I got:
Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!

Do you want to proceed? (Y/N): y
OK; writing new GUID partition table (GPT) to /dev/disk0.
Warning: Devices opened with shared lock will not have their
partition table automatically reloaded!

Caution: More than one 0xEE MBR partition found. This can cause problems
in some OSes.
Warning: The kernel may continue to use old or deleted partitions.
You should reboot or remove the drive.
The operation has completed successfully.

When I rebooted and held down the options key windows wasn't there. I am assuming that it shouldn't appear until I complete the second part is that correct? Also I do not see Windows in my finder. Did I do something wrong or did it just not work?

o2themar said:

/dev/disk0

Click to expand...

Please use /dev/rdisk0. That's with an r.

Caution: More than one 0xEE MBR partition found.

Click to expand...

That may be a problem. You might as well just create a new hybrid MBR which will fix this as well as allowing it to boot Windows, assuming the GPT is correct.