Broken GUID Partition

[AaronW]

Hi,

I hope someone can help. I've been an idiot and managed to completely screw up my GUID partitions on my MAC. Essentially I had MAC OS X 10.8.3 installed. I created 2 extra partitions one a bootcamp with Windows 8 on it, the other was to be a common disk between systems, however i was having difficulty formatting the store partition on OSX, foolishly formatted it in Windows which stuffed my boot loader for OS X. Windows then died on me and wouldn't let me reinstall so I've had to install OS X on an external drive.

I think basically I need to rebuild my partition information, but I'm not sure how to go about that, I have looked at other forums but I need someone with a few more brain cells than me....

Here is some info about /dev/disk1 (my 3 partitions). disk1s1 is Mac OS x which I need to retrieve data from, disk1s2 Windows 8 and disk1s3 Store

diskutil list /dev/disk1
/dev/disk1
#: TYPE NAME SIZE IDENTIFIER
0: FDisk_partition_scheme *500.1 GB disk1
1: Windows_LDM 410.5 GB disk1s1
2: Windows_LDM 45.2 GB disk1s2
3: Windows_LDM 44.4 GB disk1s3

From frisk -e /dev/disk1

fdisk: 1> fdisk: 1> print
Disk: /dev/disk1 geometry: 60801/255/63 [976773168 sectors]
Offset: 0 Signature: 0xAA55
Starting Ending
#: id cyl hd sec - cyl hd sec [ start - size]
------------------------------------------------------------------------
1: 42 0 0 2 - 1023 254 63 [ 1 - 801736703] LinuxSwap DR
*2: 42 1023 254 63 - 1023 254 63 [ 801736704 - 88283136] LinuxSwap DR
3: 42 1023 254 63 - 1023 254 63 [ 890019840 - 86751280] LinuxSwap DR
4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

and the result of gpt -r show /dev/disk1

start size index contents
0 1 MBR
1 801736703 1 MBR part 66
801736704 88283136 2 MBR part 66
890019840 86751280 3 MBR part 66
976771120 2048

I really appreciate any help that anyone could give.....

Thanks

 

[oldscribe]

Hi,

Think you will have to start from scratch, truly feel because you want to save data from the dead OS X partition that an Apple store appointment would be your quickest and safest option.

You can reinstall OS X yourself but all your data will be lost from that partition during the erasing session

 

[Kaveman]

You best option would be to either go in from another Mac, or remove the drive and access it from an external enclosure.

I would recommend taking it to an AppleCare Service Centre near you.

oldscribe: Apple store doesn't do data recovery.

 

[oldscribe]

Hi Kaveman,


Thank you for the hint, always assumed wrongly that the GB bar staff would retrieve data for you if you had a HD failure and wanted / needed it replaced.

 

[Kaveman]

While I think the Genius Service it fantastic, (my son is one), there are a few things to bear in mind.

1. They are insanely busy, they have about 10 minutes with the customer to locate the problem and fix, replace or book the unit in for repair. There is often a cue and they have a lot of pressure to keep moving through the cue. An AppleCare Service Centre has less time pressure and can often take the time to explore the problem and recommend non-Apple solutions.

2. AppleCare Service Centres can and will take more interest in problems with items no longer under warranty.

3. Data preservation or/and recovery is NOT covered by AppleCare and there is often an additional charge for this. The Apple Stores don't recover data (to the best of my knowledge). There is all manner of liability and damages issues. An AppleCare Service Centre may try to recover your data if you ask.

If your Apple problem is under AppleCare and I strongly recommend buying extended AppleCare, take it to an Apple Store, it is/was far more likely to be replaced. But for other needs, locate an AppleCare Service Centre near you and build a good relationship with them.

 

[AaronW]

Hi,

Thanks for all your replies so far....

I've been playing around with gdisk. This said that I had valid MBR and a corrupt GPT. Going ahead and using the GPT produced the following partition table:

Disk /dev/disk1: 976773168 sectors, 465.8 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 00001188-1184-0000-9631-0000BE350000
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 976773134
Partitions will be aligned on 8-sector boundaries
Total free space is 3909 sectors (1.9 MiB)

Number Start (sector) End (sector) Size Code Name
1 40 409639 200.0 MiB EF00 EFI system partition
2 409640 800465327 381.5 GiB AF00 Customer
3 800465328 801734863 619.9 MiB AB00 Recovery HD
4 801736704 890019839 42.1 GiB 0700 Windows
5 890021888 976773119 41.4 GiB 0700 Common
17 18376656804508598272 4613656343264362496 2.0 ZiB FFFF -931e-e97dc836
19 4179340454199885824 4179340454202923064 1.4 GiB FFFF

I've removed the partitions 17 and 19 which appear to be garbage to give:

Disk /dev/disk1: 976773168 sectors, 465.8 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 00001188-1184-0000-9631-0000BE350000
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 976773134
Partitions will be aligned on 8-sector boundaries
Total free space is 3909 sectors (1.9 MiB)

Number Start (sector) End (sector) Size Code Name
1 40 409639 200.0 MiB EF00 EFI system partition
2 409640 800465327 381.5 GiB AF00 Customer
3 800465328 801734863 619.9 MiB AB00 Recovery HD
4 801736704 890019839 42.1 GiB 0700 Windows
5 890021888 976773119 41.4 GiB 0700 Common

However now when I verify the disc it says:

Problem: The CRC for the main partition table is invalid. This table may be
corrupt. Consider loading the backup partition table ('c' on the recovery &
transformation menu). This report may be a false alarm if you've already
corrected other problems.

Caution: The CRC for the backup partition table is invalid. This table may
be corrupt. This program will automatically create a new backup partition
table when you save your partitions.
Warning! Main partition table overlaps the first partition by 34 blocks!
You will need to delete this partition or resize it in another utility.

The main problem seems to be the main partition table overlapping the first partition... I'm not entirely sure what it is referring to here.... The primary GPT is usually 34 sectors right? but my partition 1 (EFI) starts at 40 right? So there should be room? And I don't think it refers to partition 2 and 1 which start 1 sector after each other....

Any ideas please?!?

Thanks.

Aaron

 

[oldscribe]

Hi Aaron,

My one thought is to run test disk it might just give you back a bootable OS X partition.
http://thexlab.com/faqs/aht.html

& Kaveman
Great info, I always take out Apple Care just never had to use it, other than on a iPhone and the GB just replaced the unit that's were my wrong assumption came from.

 

[AaronW]

Hi,

Thanks for all your posts. I did try the X test, but it reported no hardware issues... however...

I thought I would post that I have fixed my problem above and am currently writing this from my working Mac OS X....

For anyone else who is having a similar problem. Because my GPT was corrupt I decided to create a new empty GPT and add my old paritions manually (there was enough data in my GPT to list the sectors of the partitions from previous) using gdisk.

So... I changed the default sector size from 2048 to 1 (otherwise you can't create the first EFI partition which starts at 40)

Then created the 4 individual partitions (below) using the add command. Verified the new GPT with the V command, crossed my fingers and wrote the new GPT..... within 10 seconds I could access all my data again, and on rebooting I was able to boot into my Mac OS

Number Start (sector) End (sector) Size Code Name
1 40 409639 200.0 MiB EF00 EFI system partition
2 409640 800465327 381.5 GiB AF00 Customer
3 800465328 801734863 619.9 MiB AB00 Recovery HD
4 801736704 890019839 42.1 GiB 0700 Windows

Hope this helps someone else!

Aaron

 

[oldscribe]

Hi Aaron,

Very pleased to hear your good news, thank you for posting info.