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GPT/Protective MBR problem...

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# 1  
Old 11-09-2010
GPT/Protective MBR problem...


short thing: I've done something I didn't know what happens; bad thing: I did it with my partition table.

My OS is Ubuntu 10.10. I've used GPT and now want to convert it to MBR with gdisk.
I started gdisk, chose 'r' for "transformation options" and chose 'g' to "convert GPT into MBR and exit".
Then I rebooted. Now all my programs tell me something other:

fdisk says the following (language is german):
   Gerät  boot.     Anfang        Ende     Blöcke   Id  System
/dev/sda1               1      121602   976762583+  ee  GPT

gdisk says it to be a protective MBR, but '-l' switch doesn't print any partition:
GPT fdisk (gdisk) version 0.5.1

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.

The kernel doesn't seem to detect anything, only sda* thing is /dev/sda.

partitionmanager says that there is no valid partition table.

Now, what should I do? Stupid thing is that I missed to make a backup of my first sectors before.
Remember, the only thing I want is to be able to read my partitions on sda again and to have an MBR on it in the end.


Last edited by Blackbird; 11-09-2010 at 03:31 PM..
# 2  
Old 11-09-2010
Humm, the conversion from GPT to MBR by gdisk is a best-faith attempt only according to the man page. No guarantees, especially if there were no free blocks between the partitions.

You could try the -c option to load the backup partition table but I suspect that it will contain nothing.
# 3  
Old 11-10-2010
Oh dear. Lucky me that a made a backup of my data before.

I think I will just create a new MBR and restore my backups...
# 4  
Old 11-10-2010
Yes, that is the best plan. Glad you had a backup. It is my opinion that utilities such as gdisk should not attempt to automatically convert from MBR to GPT and visa versa. Too many edge cases where things can go wrong.

Last edited by fpmurphy; 11-10-2010 at 10:15 AM..
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