One can convert MBR partition tables to EFI partition tables non-destructively.

You've come to this page because you've said something similar to the following:

The only way to convert from a disc partitioned with the MBR partition table scheme to the EFI partition table (also known as the GUID partition table, or GPT) scheme is destructively. You have to delete all existing partitions from the disc before converting.

This is the Frequently Given Answer to such statements.

That is false. It is quite possible to non-destructively convert from the MBR partition table scheme to the EFI partition table scheme. At least two tools exist for doing so — one published and one (currently) not. Microsoft's Disk Manager and diskpart have the limitations of only being able to convert empty discs. But they are far from being the only tools capable of converting partition tables, and the other tools available don't share Microsoft's limitations.

Here's the unpublished tool (dasdpart) in action, demonstrating such a conversion:

[H:\]inspect 0|head /11
Disc GUID: 00000000-3d1b-17e3-8201-020000000000
The partitionable area is blocks 1 to 60067034 inclusive (28.6GiB).

                                       0a IBM Boot Manager
               63        16064        16002    7.8MiB
                                       07 MS Data
            16065     16434494     16418430    7.8GiB
[H:\]mbrtogpt 0
[H:\]inspect 0|head /13
There are 4 entries in the partition table, using 1 sectors.
Partition entries are 128 bytes long.
Disc GUID: 6a2f4b65-4c19-473d-a401-5635953aa27a
The partitionable area is blocks 3 to 60067032 inclusive (28.6GiB).

     083e58f1-ff57-4b08-9ab7-f7433966a104 IBM Boot Manager
               63        16064        16002    7.8MiB
     ebd0a0a2-b9e5-4433-87c0-68b6b72699c7 MS Data
            16065     16434494     16418430    7.8GiB

The published tool is Rod Smith's gdisk. If you have a Linux, FreeBSD, or MacOS version 10 system, you can just run it directly. If not, then notice that M. Smith lists two sources for "emergency rescue" CD-ROMs that one can bootstrap a system with, which contain gdisk.

© Copyright 2010 Jonathan de Boyne Pollard. "Moral" rights asserted.
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