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Sanjaya83 Author

Level 1

1 points

Can't boot into windows after resizing partitions

I tried to resize my bootcamp and mac partitions recently

I cannot boot into windows now

Get an error about missing MBR

Do you think you could help me here?

I read about using GPT fdisk on another thread

These are the results I got from it

Wanted to check before doing anything

Sanjayas-MacBook-Pro:~ sanjaya83$ sudo fdisk /dev/disk0

Disk: /dev/disk0 geometry: 38913/255/63 [625142448 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 - 349609376] HFS+

3: AB 1023 254 63 - 1023 254 63 [ 350019016 - 1269536] Darwin Boot

4: 0C 1023 254 63 - 1023 254 63 [ 351289344 - 273852416] Win95 FAT32L

Sanjayas-MacBook-Pro:~ sanjaya83$ sudo gdisk /dev/disk0

GPT fdisk (gdisk) version 1.0.1

Warning: Devices opened with shared lock will not have their

partition table automatically reloaded!

NOTE: Write test failed with error number 1. It will be impossible to save

changes to this disk's partition table!

You may need to deactivate System Integrity Protection to use this program. See

https://www.quora.com/How-do-I-turn-off-the-rootless-in-OS-X-El-Capitan-10-11

for more information.

Partition table scan:

MBR: hybrid

BSD: not present

APM: not present

GPT: present

Found valid GPT with hybrid MBR; using GPT.

Command (? for help): p

Disk /dev/disk0: 625142448 sectors, 298.1 GiB

Logical sector size: 512 bytes

Disk identifier (GUID): 55739070-E42E-4414-947D-F1AAD2EB65D0

Partition table holds up to 128 entries

First usable sector is 34, last usable sector is 625142414

Partitions will be aligned on 8-sector boundaries

Total free space is 1453 sectors (726.5 KiB)

Number Start (sector) End (sector) Size Code Name

1 40 409639 200.0 MiB EF00 EFI System Partition

2 409640 350019015 166.7 GiB AF00 Customer

3 350019016 351288551 619.9 MiB AB00 Recovery HD

4 351289344 625141759 130.6 GiB 0700 BOOTCAMP

Command (? for help):

MacBook Pro (13-inch Early 2011), OS X El Capitan (10.11.1)

Posted on Dec 1, 2015 5:12 PM

152 replies

Loner T

Level 9

59,513 points

Feb 16, 2016 7:40 AM in response to zero7404

Even 3 4 5 is not a guarantee of safety. It is non-standard. There is no way to predict what Apple software has designed/planned for the future. The safest route is to use a UEFI Mac, which has no Hybrid MBR, which implies using a 2013+ Mac. The downside is that W7 is not supported on some models.

You have mentioned a Late 2013 model, which would need a re-installation.

zero7404

Level 3

813 points

Feb 16, 2016 7:39 AM in response to Loner T

i was meaning to touch on that subject: since I have windows 10 and it's uefi-compatible, why can't i remove the MBR all together and go with straight GPT throughout the disk ?

is that possible ?

Loner T

Level 9

59,513 points

Feb 16, 2016 7:45 AM in response to zero7404

sakman74 wrote:

i was meaning to touch on that subject: since I have windows 10 and it's uefi-compatible, why can't i remove the MBR all together and go with straight GPT throughout the disk ?

is that possible ?

Yes. If you upgraded from W7/W8+, it carried over as a BIOS/MBR installation.

zero7404

Level 3

813 points

Feb 16, 2016 8:04 AM in response to Loner T

i took the windows 10 upgrade from 8.1, since my windows partition is reporting MBR.

is there a reasonably safe way to convert the existing windows partition to GPT without doing a new clean install of windows 10 ?

Loner T

Level 9

59,513 points

Feb 16, 2016 8:59 AM in response to zero7404

There is no practical method to convert BIOS to EFI. W10 should allow you a clean re-installation. Back up W10 before you use BCA to remove W10. You can use DU to create Free Space for an EFI W10 installation. Create all your partitions before you install W10.

zero7404

Level 3

813 points

Feb 16, 2016 9:55 AM in response to Loner T

if i wipe out the w10 partition, would i be able to delete the mbr completely, then do a fresh install of win10 on gpt partition without wiping out the essential partitions (recovery, hfs+) ?

Loner T

Level 9

59,513 points

Feb 16, 2016 11:17 AM in response to zero7404

Since your original W7/W8 installation was MBR (upgraded to W10), use only BCA to remove Windows. It will also cleanup the MBR, leaving a GPT-only disk. You can then use DU to create partition(s) for W10 (Free Space) and Shared (choose appropriate file system). Re-install W10 using EFI Boot.

zero7404

Level 3

813 points

Feb 16, 2016 12:28 PM in response to Loner T

im willing to give that a shot later this year, perhaps when i upgrade my storage capacity or sell my mbp and get a newer one.

thanks

steve359

Level 6

17,175 points

Feb 16, 2016 12:34 PM in response to Loner T

Not to threadjack, sir ... maybe you can perform miracles ... mac Mountain not working after installing linux

Loner T

Level 9

59,513 points

Feb 16, 2016 12:58 PM in response to steve359

steve359 wrote:

Not to threadjack, sir ... maybe you can perform miracles ... mac Mountain not working after installing linux

Thanks, steve359 . Posted on that discussion.

zero7404

Level 3

813 points

Feb 17, 2016 4:51 AM in response to Loner T

so, to get into EFI boot, I would hold down the option key and select the EFI disk which contains the Windows 10 installation media, correct ?

after i use BCA to cleanup the existing windows installation, I can confirm that the MBR is gone by running gdisk to see if an MBR is present ....

Loner T

Level 9

59,513 points

Feb 17, 2016 4:59 AM in response to zero7404

Removing W10 using BCA will clean up the partition and remove the MBR. Verify using Gdisk r,o or Fdisk.

Your 2013 Mac should build a USB Installer. If you use Alt/Option, you will both, Windows (Legacy) and EFI Boot (UEFI). Choose EFI Boot.

zero7404

Level 3

813 points

Feb 17, 2016 12:56 PM in response to Loner T

thanks.

is it your opinion that the "safest" disk arrangement I can run with multiple OS's (os 10 + windows 10) for a single physical disk setup on my late 2013 mbp would be GPT-only ?

For flash usb drives, I would like to partition to have 3 or 4 partitions: one for Clonezilla, one for HDM, one with the same things I would find by booting recovery mode (with the version of DU that's available in Internet recovery) and the remainder as extFAT for files storage in general.

possible to do that using DU within os 10 ? I have to check whether I can get HDM to install it's Startup disk on a specific partition rather than take over and format an entire flash usb drive. What is interesting about HDM's startup disk is that it looks just like recovery mode with the tools normally available in recovery (it must copy them directly from the recovery partition).

Loner T

Level 9

59,513 points

Feb 17, 2016 1:04 PM in response to zero7404

sakman74 wrote:

is it your opinion that the "safest" disk arrangement I can run with multiple OS's (os 10 + windows 10) for a single physical disk setup on my late 2013 mbp would be GPT-only ?

EFI is much more efficient. EFI requires GPT-only. A MBR is pain.

For flash usb drives, I would like to partition to have 3 or 4 partitions: one for Clonezilla, one for HDM, one with the same things I would find by booting recovery mode (with the version of DU that's available in Internet recovery) and the remainder as extFAT for files storage in general. possible to do that using DU within os 10 ?

You will need to partition using GPT. Flash drives may not support multiple partitions well though.

I have to check whether I can get HDM to install it's Startup disk on a specific partition rather than take over and format an entire flash usb drive. What is interesting about HDM's startup disk is that it looks just like recovery mode with the tools normally available in recovery (it must copy them directly from the recovery partition).

The OSX Recovery HD is a better maintained solution. You can create this on an external disk as well.

Middow

Level 1

18 points

Jul 20, 2016 7:30 PM in response to Loner T

can you help out with Re: unable to boot using bootcamp after creating new partition

Can't boot into windows after resizing partitions