Convert existing disk to GPT

Posted on 2012-08-14
Medium Priority
Last Modified: 2014-11-23
I have a virtual server running on a Hyper-V machine that I need to increase the size of the data drive on.  I know I can just shut down the VM, increase the vhd, and then reboot it and extend the volume and the space should be there.  Problem is, I need the disk to be converted to a GPT disk instead of an MBR.

I found this article on doing this and it seems simple:


The data drive isn't currently extended so it shouldn't be a problem I don't think, as long as it's ok if I extend it afterwards.  

Has anyone successfully done this before while preserving the data or should I just backup everything and create a new vhd and then restore the data.  The latter is a big task since it's about 600GB already and has numerous shares and different permissions for each share.  The process in the article should work as long as I extend the volume AFTER I add the new free space correct?

Thanks for the help!
Question by:ryan_johnston
LVL 17

Assisted Solution

by:Brad Bouchard
Brad Bouchard earned 1000 total points
ID: 38292859
I've always understood the change from GPT to MBR and MBR to GPT to be something you can't preserve the data on.  I'd backup and restore even if it is longer, it's better than losing data.

You can change a disk from GPT to MBR as long as the disk is empty.
Source:  http://technet.microsoft.com/en-us/library/cc737510(v=ws.10).aspx

Accepted Solution

btetlow-expert earned 1000 total points
ID: 38292872
The "tool" noted on that page may in fact work --- it is rather interesting...

So far as I know however, converting to GPT from MBR is destructive, so I would definitely be wary of such a tool that while it might work........you're using it on your live data.

That's not to say I wouldn't try it -- but I don't think I would risk it on live data....

Notes from that link do suggest it would work.....but..... Still....     I guess IF you backup everything on the drive first, IF it breaks, then at least you still have the data....

Note that there is a NEWER release listed at:  http://sourceforge.net/projects/gptfdisk/files/gptfdisk/0.8.5/gdisk-binaries/

Always good to use latest version if possible...

Would love to know if it REALLY works....

Good luck....

Author Comment

ID: 38292882
Bouchard, that's what I've always thought as well and saw that same technet.

btetlow, That's the same thing I was thinking.  That server is always backed up daily so I know I have a backup, but running a manual backup at the time of conversion will take too long.  I guess I'll have an early morning so I can get to it before people come in.  Thanks for the sourceforge link.

Regardless, this will be done tomorrow morning so we'll find out what actually happens...
Has Powershell sent you back into the Stone Age?

If managing Active Directory using Windows Powershell® is making you feel like you stepped back in time, you are not alone.  For nearly 20 years, AD admins around the world have used one tool for day-to-day AD management: Hyena. Discover why.

LVL 17

Expert Comment

by:Brad Bouchard
ID: 38292946
What I'm guessing that program you linked to does is actually back your data up somewhere on its own so that it basically clones your HDD, converts it, then restores that clone to the new GPT disk.  That may be a false theory, but that's my guess.

Author Comment

ID: 38292990
If that's what it does, then that would provide an issue since this site doesn't have a SAN available to me and I'd have no space to put the clone anywhere :(

I'm currently researching to see if Hyper-V has an export/snapshot option that I'd be able to restore to a new drive.  I know Citrix XenServer has this option but I haven't used Hyper-V for very long.
LVL 17

Expert Comment

by:Brad Bouchard
ID: 38293045
I love XenServer for that.  Don't quote me on it, but I can't imagine Hyper-V or ESX/ESXi wouldn't also have that feature.

Author Closing Comment

ID: 38293909
I couldn't tell you if this would work or not.  We have decided not to convert the existing disc.  We were able to remove a development VM which free'd up enough space to create another vhd.

The solution is to create and mount the new vhd as a GPT disk and then use the File Server Migration Wizard to move all the data on the drive.  This seemed to be the best option since it didn't look like Hyper-V had the same feature as Xen as far as the export goes.  It can snapshot but that's about it (Either that or it's not easy to find how to do it....).

And the best part about the FSMW is that it will automatically stop the old shares and share the new folders on the new drive.  

Thanks both of you for your input.

Expert Comment

ID: 40461179
I figured out a way to do it after having the issue of the blinking cursor and the message that I had the wrong Windows version when trying to repair it. It took about 8 hours of research and figuring it out but I got it to work. I made a ten minute You Tube video that walks you through it. I have been an Expert Exchange subscriber for years and you all have helped me out, so I am giving you one back.


Let me know if it helps.

Featured Post

[Webinar] Cloud and Mobile-First Strategy

Maybe you’ve fully adopted the cloud since the beginning. Or maybe you started with on-prem resources but are pursuing a “cloud and mobile first” strategy. Getting to that end state has its challenges. Discover how to build out a 100% cloud and mobile IT strategy in this webinar.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article explains how to install and use the NTBackup utility that comes with Windows Server.
This article shows how to use a free utility called 'Parkdale' to easily test the performance and benchmark any Hard Drive(s) installed in your computer. We also look at RAM Disks and their speed comparisons.
This tutorial will walk an individual through locating and launching the BEUtility application and how to execute it on the appropriate database. Log onto the server running the Backup Exec database. In a larger environment, this would generally be …
To efficiently enable the rotation of USB drives for backups, storage pools need to be created. This way no matter which USB drive is installed, the backups will successfully write without any administrative intervention. Multiple USB devices need t…
Suggested Courses

840 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question