How to change Disk Signature from MBR to GPT and recover partitions

Computer Help and Discussions Software
1

I have a non-system Data-only 600 GB HDD which was GPT and had a typical GUID Disk ID - e.g. baf784e7-6bbd-4cfb-aaac-e86c96e166ee.

I booted into a Linux utility on a Boot CD, but the sysLinux loader crashed and the PC restarted so I then booted into Windows 7 Ultimate.

Windows found that the GPT disk had changed to the same MBR Disk ID 000FA830 as a 1000 GB HDD,

which was and remains MBR, and due to Signature Conflict the 1000 GB HDD was put off-line.

The 600 GB HDD remained on-line but the main partition is now "Unallocated" and other partitions are RAW.

A Data Recovery tool has recovered the original files with the original names to another HDD,

but many 6 GB files may have been fragmented and the pieces connected in the wrong sequence (but the file sizes are absolutely the correct number of bytes).

I suspect that if I can change the Disk ID back to GUID then Windows might recognise the partitions are not the same as MBR,

and possibly :-

Windows will instantly see the files and fit the fragments correctly - in which case I will know I am dreaming ; or

My Data Recovery tool may find the metadata etc to put the fragments together in the correct order.

Is there any FREE tool that can change the Disk ID without Data Loss ?

Minitool Partition Wizard includes a Partition Recovery Wizard that even now can identify the precise boundaries of the missing partitions,

This has worked perfectly in the past when my Laptop lost all its partitions.

But I emailed Minitool support and they advised that it was only suitable for MBR disks.

Is there any FREE tool that can Recover lost GPT Partitions ?

Fortunately before the disaster I had backed up to an external HDD, and only one file was created since the backup.

I can live without that file so will not be paying for software.

Regards

Alan

2

Bit out of my league this Alan. Had a look around for you, any help here

http://www.howtohaven.com/system/change-disk-signature.shtml

http://forums.fedoraforum.org/showthread.php?t=273621

Although not exactly your issue this 2 page thread shows the problems that people can have with lost partitions on a GPT drive

http://hardforum.com/showthread.php?t=1632902

3

Thanks Hazel

http://www.howtohave...signature.shtml

This was the most promising- it works under Windows and can I use my browser to follow the instructions line by line.

Unfortunately I get this error :-

DISKPART> UNIQUEID DISK ID=21EC2020-3AEA-1069-A2DD-08002B30309D

The specified identifier is not in the correct format.

Type the identifier in the correct format:

in hexadecimal form for an MBR disk or as a GUID for a GPT disk.

I have not yet found any reason for that error.

Is it possible I have been misled by Linux topics which differ from Windows format in a Big-Endian / Little-Endian fashion, i.e.

21EC2020-3AEA-1069-A2DD-08002B30309D

08002B30309D-A2DD-1069-3AEA-21EC2020

I know I have full authority because I launched a second instance of DISKPART for the sole purpose of independently and instantly observing the disk ID,

It confirmed that the first instance was instantly successful with both of these commands :-

UNIQUEID DISK ID=000FA832

and

UNIQUEID DISK ID=000FA830

So for some reason DISKPART is happy to change one MBR ID value to another MBR ID value, but NOT to a GPT ID value.

Further advice would be appreciated.

re http://hardforum.com...d.php?t=1632902

He lost his partitions and all his data beyond recovery after defragging his drive.

I am thankful that ever since there was DOS my phobia against defragging has protected me from that situation. :)

After losing partitions I have recovered the data,

and even though some of my 6 GB to 6.7 GB Macrium Reflect image backup files are corrupted,

all of my 100 MB to 2 GB files image backup files are perfectly validated.

In post #17 I read

The board supports UEFI, but seems not to fully support GPT and 3 TB drives

I have an older NON-UEFI motherboard and am concerned that it also cannot fully support GPT (in some way I do not understand).

I have read that GPT has a "linked list" of partition tables so that corruption does not lose all the partitions, and this makes it more secure,

whereas MBR keeps its partition table in one place at the beginning of the disk so everything is lost if that table is lost.

Unfortunately when GPT theory meets GPT reality there are many total loss incidents - I have not yet seen any topic where some GPT partitions escaped the fate of their neighbours.

I have now downloaded a few Rescue Boot ISO's that included gdisk.

I initially plan to only inspect the diagnosis,

and then boot back into Windows and reconsider.

Regards

Alan

4

Would using the no error parameter listed here help do you think?

http://technet.microsoft.com/en-us/library/cc730793(v=ws.10).aspx

Also this page may help Alan, seems to be written by someone who knows what he is talking about..

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

5

Thanks

I tried appending noerr with the command string shown in the first link

uniqueid disk id=baf784e7-6bbd-4cfb-aaac-e86c96e166ee noerr

Unfortunately the error message was the same - it took me no further to success.

I think the only benefit of "noerr" is that in its absence a Diskpart script instantly aborts upon error and subsequent script commands are not executed.

When it is present then subsequent script commands are performed,

which may be a very bad thing if you have selected DISK 2 and performed actions on that, and then execute

DISK SELECT O NOERR

CLEAN ALL

The result might be secure deletion of every sector on DISK 2 if you had accidentally not selected disk number zero but the disk between N and P

Forums you linked to in your first post already took me to

http://www.rodsbooks...disk/gdisk.html

From there I used links to a few Boot Rescue ISO's that include gdisk.

I am happy to launch gdisk and observe its diagnosis.

I have not yet tried booting those ISO's but fear that they may be unable to show me Rod's on-line instructions,

and suspect that I would need a full Linux distro that includes gdisk and a browser.

I fear that gaining proficiency with Linux will take me too much time and effort.

Regards

Alan

6

Well that's me out of ideas now. It is a very tricky and involved subject which I'm sure you have found out.

Good luck :)

7

Thanks for trying.

If no one else has any easy solutions in the next few days I will give up and just clean the drive and start afresh - almost certainly as an MBR not a GPT.

N.B.

Earlier today I found that "UNIQUEID DISK" was able to read and display the current ID regardless of whether the HDD had been set "off-line" or "on-line",

but "UNIQUEID DISK ID=000FA832" failed with a write protected error when the HDD was "off-line"

I guess that when running under Windows no application and no malware can damage the Disk Signature or write to the contents of the HDD.

I hope this also puts a stop to any Linux Boot mischief doing any sort of damage to it in the future.

Previously :-

My 931 GB HDD held only small partitions D:\ and H:\ which were backed up (along with my SSD) by Macrium Reflect,

but most of its space was otherwise unallocated ;

My 596 GB HDD was mostly E:\ for holding Macrium Reflect image backups at E:\Images and my browser download folder at E:\Downloads,

but with adequate unallocated space for any Virtual Machine etc experiments.

And all Image backups were occasionally copy/verified by TeraCopy via eSATA to an external HDD that was normally powered down.

eSATA backups were complete but done in groups because, unlike my USB2 external Drive,

the eSATA Drive was not considered "Removable" and could not be safely removed but only disabled (with luck)

and when first connected it was only detected after telling Zentimo to "Detect Hardware Changes",

and eventually it would find the eSATA and report it Disabled and I would have to enable it.

I got lazy with how often I allowed a backlog before duplicating to eSATA.

I have now added partition E:\ to the 931 GB HDD for the purpose of E:\Downloads and E:\Images.

For one extra level of protection on top of eSATA copies I plan to :-

Give my 596 GB HDD a partition that Windows Disk Management will "Mount in the following empty NTFS folder : E:\ImagesCopy".

and will use TearCopy to Duplicate E:\Images to E:\ImagesCopy whenever I create a new backup,

For a second extra level of protection I plan to keep that HDD offline,

apart from when TeraCopy is duplicating to it.

Regards

Alan