Recently my exchange server 2016 DAG was running out of space, my database reaches 2 TB and the MBR cannot be extended anymore, so I need to convert to GPT. I tried Diskpart, which is a good builtin tool using the following command, but it fails and returns the following error
Virtual Disk Service error:
The specified disk is not convertible. CDROMs and DVDs
are examples of disks that are not convertable.
Based on some googling and reading it seems that this command will work fine if I clear the disk (format it) which cause a full data lost on the disk, and this is not applicable on my case, I have 2 exchange server 2016 with 2TB of data on one of the disk, resyncing the data will take several days.
I find this super tools
Just download it and place it on drive C: or whatever drive other than you want to convert and run the following command gptgen.exe, the output will be
where device_path is the full path to the device file,
Available arguments (no "-wm"-style argument combining support):
-c nnn, --count nnn: build a GPT containing nnn entries (default=128)
-h, --help, --usage: display this help message
-k, --keep-going: don't ask user if a boot partition is found
-m, --keepmbr: keep the existing MBR, don't write a protective MBR
-w, --write: write directly to the disk, not to separate files
One of the required parameters is the disk number and we can get it from Diskpart, using the following command
>> List disk
You need to know the disk number you want to convert. Let's assume that the disk you want to convert is disk 1, just remember the number, now exit Diskpart and navigate to GPTGen and execute the following command
gptgen.exe -w \\.\physicaldrive1
The -w parameter is used to write GPT table and is required in the converting process, just make sure to write the correct disk number, in my case, it's 1.
The output will be similar to
That easy, GPT without losing any data
No need to reboot, even though I recommend to reboot and make sure that everything is working fine. Also, I recommend before doing, try to minimize IO on the disk, place the server in maintenance mode, turn the services off, and also backup your data if you can. Gptgen have the option to backup the current MBR before converting it.