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I have just installed ubuntu 16.04 on a macbook pro 7.1. I was having some difficulties, but eventually got it to work.

Based on my original difficulties pertaining to the video card (see here: Problem installing 16.04 on Mac: Created BIOS boot partition), i have found another problem with the GPT table.

When I run gparted on from a live USB i get the following error: "The primary GPT table is corrupt, but the backup appears OK, so that will be used"

I was told in the last thread that this was a problem that i had to fix. So I downloaded gdisk. However when I run that from within OSX i don't see any errors. Also running gparted from within the ubuntu install does not give the error.

gdisk /dev/disk0

gives:

GPT fdisk (gdisk) version 1.0.1

Warning: Devices opened with shared lock will not have their
partition table automatically reloaded!
Partition table scan:
  MBR: hybrid
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with hybrid MBR; using GPT.

p command gives:

Disk /dev/disk0: 488397168 sectors, 232.9 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 00000B5C-4C91-0000-C021-000078700000
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 488397134
Partitions will be aligned on 8-sector boundaries
Total free space is 2293 sectors (1.1 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1              40          409639   200.0 MiB   EF00  EFI system partition
   2          409640       458838111   218.6 GiB   AF00  Customer
   3       458840064       480540671   10.3 GiB    8300  
   4       480540672       488396799   3.7 GiB     8200

v command gives:

No problems found. 2293 free sectors (1.1 MiB) available in 3
segments, the largest of which is 1952 (976.0 KiB) in size.

Also when I run gparted from within the ubuntu install (i.e. not from the live USB) no errors appear.

So what i am trying to work out is why i get errors when i run gparted from the live instance, and whether this is a cause for concern given that no problems appear when running gparted from the install and goven that gdisk finds no errors.

All help is much appreciated.

Community
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MorrisseyJ
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  • It says you have hybrid MBR/gpt. Only if you had an old dual boot with Windows that only booted with BIOS/MBR configuration on gpt drive would you ever want that. http://www.rodsbooks.com/gdisk/hybrid.html convert hybrid to protective MBR gdisk experts commands p, x, n, p, w http://askubuntu.com/questions/650194/repair-windows-boot-loader-after-installing-ubuntu-on-macbook-pro – oldfred Sep 24 '16 at 20:35
  • It's conceivable that the version of GParted on the live USB is older than what's installed on your computer, and the older version has a bug that's causing it to misidentify something harmless as a problem. This might or might not be related to the hybrid MBR. If I'm right, you can ignore the issue -- although removing the hybrid MBR is probably advisable. For a further diagnostic, I recommend you run gdisk from Ubuntu, issuing the same p and v commands you did in OS X, and compare the results. If there's a more serious problem, gdisk in Ubuntu should squawk. – Rod Smith Oct 04 '16 at 13:47

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