Convert EFI System partition to GPT without losing data

[Xiphosm3]

Hey all, last night I noticed one of my existing 4TB GPT disks went missing. I checked Disk Manager this morning and noticed it was changed from a GPT Data Partition to an GPT EFI System Partition.

I have no idea HOW it changed partition types over. If I use Minitool Partition WIzard, I can still see the files on the disk, but can't access them. I can't restore the partition either through Partition Wizard.

I found a guide online of using GPT fdisk to change it but I am concerned it will overwrite all the existing data (currently have over 3TB of data on the disk). This is what it stated:

For the benefit of others, use gdisk 0: (substitute the number of the affected drive). Type p to print the list of partitions. The EFI System Partition will have a type of EF00. Enter t to change the type, select the number of the partition, and then type the code for the standard Windows partition, which is 0700. w will then write the changes, and after a reboot you should be back to normal.

Two questions:
1. Is there any other way to convert that partition back to something usable without data loss?
2. Any idea how this happened? The drive is in an eSATA enclosure and I did swap controller cards last night but this is the only disk affected.
3. Is the guide I found going to work and not delete data?

 

[ArtPog]

FIRST OF ALL - AND THIS IS IMPORTANT - UNDER NO CIRCUMSTANCES SHOULD YOU ATTEMPT ANY SORT OF A CONVERSION PROCESS WITHOUT FIRST CLONING THE CONTENTS OF THE DISK TO ANOTHER DISK. THIS IS ABSOLUTELY CRUCIAL, CAPICHE? THESE CONVERSION OPERATIONS ARE NOT A CUT & DRIED PROCESS AND IT'S QUITE COMMON FOR THE PROCESS TO GO AMISS OR COMPLETELY FAIL, ENDING WITH THE LOSS OF DATA.

While I've carried out a number of MBR-to-GPT & GPT-to-MBR conversions, I've never experienced the type involved in your query. So I'm hesitant to offer you any advice relevant to your situation.

The gdisk program has been used by many users successfully, but it is a complicated/awkward program to undertake in my experience.

As a general proposition we use various third-party partition management type programs to carry out the conversion processes I indicated above. But again, I have no idea how successful they would be in your type of situation.

 

[Xiphosm3]

FIRST OF ALL - AND THIS IS IMPORTANT - UNDER NO CIRCUMSTANCES SHOULD YOU ATTEMPT ANY SORT OF A CONVERSION PROCESS WITHOUT FIRST CLONING THE CONTENTS OF THE DISK TO ANOTHER DISK. THIS IS ABSOLUTELY CRUCIAL, CAPICHE? THESE CONVERSION OPERATIONS ARE NOT A CUT & DRIED PROCESS AND IT'S QUITE COMMON FOR THE PROCESS TO GO AMISS OR COMPLETELY FAIL, ENDING WITH THE LOSS OF DATA.

While I've carried out a number of MBR-to-GPT & GPT-to-MBR conversions, I've never experienced the type involved in your query. So I'm hesitant to offer you any advice relevant to your situation.

The gdisk program has been used by many users successfully, but it is a complicated/awkward program to undertake in my experience.

As a general proposition we use various third-party partition management type programs to carry out the conversion processes I indicated above. But again, I have no idea how successful they would be in your type of situation.

Appreciate the help. I don't quite have the drive space right now to transfer it all off. Is there any way to convert it to standard GPT without a complete wipe?

 

[Alabalcho]

1. Go to a store.
2. Buy 4TB drive.
3. Save your data
4. Return that 4TB drive.

 

[ArtPog]

FIRST OF ALL - AND THIS IS IMPORTANT - UNDER NO CIRCUMSTANCES SHOULD YOU ATTEMPT ANY SORT OF A CONVERSION PROCESS WITHOUT FIRST CLONING THE CONTENTS OF THE DISK TO ANOTHER DISK. THIS IS ABSOLUTELY CRUCIAL, CAPICHE? THESE CONVERSION OPERATIONS ARE NOT A CUT & DRIED PROCESS AND IT'S QUITE COMMON FOR THE PROCESS TO GO AMISS OR COMPLETELY FAIL, ENDING WITH THE LOSS OF DATA.

While I've carried out a number of MBR-to-GPT & GPT-to-MBR conversions, I've never experienced the type involved in your query. So I'm hesitant to offer you any advice relevant to your situation.

The gdisk program has been used by many users successfully, but it is a complicated/awkward program to undertake in my experience.

As a general proposition we use various third-party partition management type programs to carry out the conversion processes I indicated above. But again, I have no idea how successful they would be in your type of situation.

Appreciate the help. I don't quite have the drive space right now to transfer it all off. Is there any way to convert it to standard GPT without a complete wipe?

As I indicated, you could try one of the third-party partition management programs and trust that the conversion process would go without a hitch. Frankly, it's not what I would attempt without first carrying out what I stated in my cautionary note. But you "pays yer muny and you takes yer cherce"...