Re: [Gptfdisk-general] gdisk error

[Rod S. <rod...@ro...>]

On 11/30/2011 10:42 PM, Conrad G T Yoder wrote:
> I have a MacBook Pro, running OS X 10.6 with, of course, a GPT Disk.
> The OS X Disk Utility reports no problems with the drive, but when I
> try to repartition the drive, Disk Utility does not allow me to
> resize partitions. When I try to use the OS X command-line tool, I
> get the error, "Error: -9939: The partition cannot be resized."
> 
> So I downloaded GPT fdisk and ran gdisk. Upon starting it, I get the
> messages:
> 
> 
> 
> GPT fdisk (gdisk) version 0.8.1
> 
> Type device filename, or press <Enter> to exit: /dev/disk0
> Warning! Main and backup partition tables differ! Use the 'c' and 'e' options
> on the recovery & transformation menu to examine the two tables.
> 
> Warning! One or more CRCs don't match. You should repair the disk!
> 
> Partition table scan:
>   MBR: hybrid
>   BSD: not present
>   APM: not present
>   GPT: damaged
> 
> Found valid MBR and corrupt GPT. Which do you want to use? (Using the
> GPT MAY permit recovery of GPT data.)
>  1 - MBR
>  2 - GPT
>  3 - Create blank GPT
> 
> Your answer: 
> 
> 
> 
> And I'm not sure what the next best step here is. Any suggestions?
> Let me know if you would like more info.

At this point, you should definitely select option 2 (GPT). After this
point, though, you may encounter problems because there's been damage to
one of the partition tables. You should probably check both partition
tables by using the 'c' and 'e' options on the recovery & transformation
menu, as the program suggests, to see which one is correct. (Use 'p'
after loading each table to view it, and use your own knowledge of what
the partition table SHOULD look like to determine which is correct.)

For more on recovering GPT data, see my Web page on the topic:

http://www.rodsbooks.com/gdisk/repairing.html

It's also conceivable you'll need to re-create the hybrid MBR; but you
shouldn't worry about that just yet. You'll know you'll need to do that
if a 'v' operation reports a mismatch between the GPT and MBR data or if
you can't boot Windows after you make your repairs to the GPT data.

As a side comment, it's possible that this damage was caused by Windows
disk encryption tools or a GPT-unaware boot loader. If you've used such
tools, you should uninstall them ASAP. I recommend first repairing the
disk, then backing up the GPT data (using 'b' on gdisk's main menu),
then removing the offending software, then checking the disk again for
damage (since removing the software could cause more damage to the disk).

If you need more advice, feel free to send another e-mail to the list,
or to me directly.

Good luck!

-- 
Rod Smith
rod...@ro...
http://www.rodsbooks.com