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Hetzner - How to convert a OS disk to a GPT disk without loosing data?
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Hetzner - How to convert a OS disk to a GPT disk without loosing data?

I have a E5-1245V2 with 2x3 TB HDD. I have used a Windows template to install Windows Server from Rescue.
The issue I have is that the first disk, the OS disk, is not a GPT disk, and I can't change it under disk manager. So I'm loosing 700+ GB.

How do I convert the disk to a GPT disk so I can use the missing 700+ GB, without loosing any data. It's a production server, so I hope I can use some free software to do the job?

Is it possible?

Comments

  • RhysRhys Member, Host Rep

    There's a simple guide on the arch wiki that i've used in the past to do this.

  • @MeltedLux said:
    There's a simple guide on the arch wiki that i've used in the past to do this.

    Will this work on a Windows server? It's seems like it's for Linux?

  • RhysRhys Member, Host Rep

    @myhken said:

    @MeltedLux said:
    There's a simple guide on the arch wiki that i've used in the past to do this.

    Will this work on a Windows server? It's seems like it's for Linux?

    It should do but I've never done it.

  • GPT requires UEFI boot afaik.

  • @teamacc said:
    GPT requires UEFI boot afaik.

    OK, so I get some issues there. I do not know if Hetzner E3 servers comes with UEFI.

  • mfsmfs Banned, Member
    edited February 2017

    teamacc said: GPT requires UEFI boot afaik.

    AFAIK, that could (still) be correct for Windows (I don't know) whilst it's not correct for Linux et al

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

    Many Internet sources, particularly discussion groups, assert that it's impossible to boot a GPT disk on a BIOS computer. This is nonsense—or at least, it's true only of certain OSes. Windows, in particular, is behind the times on this score, as described shortly. I personally have successfully booted both Linux and FreeBSD on GPT-only computers with BIOSes.

    and I've done it too; also https://en.wikipedia.org/wiki/BIOS_boot_partition

    The BIOS boot partition is a partition on a data storage device that GNU GRUB uses on legacy BIOS-based personal computers in order to boot an operating system, when the actual boot device contains a GUID Partition Table (GPT). Such a layout is sometimes referred to as BIOS/GPT boot.

    anyway, since OP requires Windows... I really don't know. What I know is that I wouldn't perform such migration "live" on a production server. It may be better to move the production stuff elsewhere, rebuild the server and restore backups.

    Thanked by 2Rhys maverickp
  • RhysRhys Member, Host Rep
    edited February 2017

    @mfs said:
    anyway, since OP requires Windows... I really don't know. What I know is that I wouldn't perform such migration "live" on a production server. It may be better to move the production stuff elsewhere, rebuild the server and restore backups.

    Definitely.

  • never done it on a vps but have converted windows to gpt with no data loss with easus partiton mamager before as long as you have kvm access shouldnt be a problem

  • Use "rufus" with option "uefi with gpt" and make a bootable usb Drive then use a software USB to iso, use your iso to install Windows.

  • myhken said: Will this work on a Windows server? It's seems like it's for Linux?

    Yes, and no

    you "can" convert it however you will need to use a windows disk to recover the boot files (for the new efi system)

  • Better back up the disk before doing anything like that. Get a Hetzner Storagebox plan big enough to hold everything, back it all up, do your operation, and then if you want you can downgrade the storage box to 100GB. You have to keep the storage active for the whole month but they charge you by its size computed on a daily basis, so if it's 2000GB for a few days and 100GB the rest of the month, that's much cheaper than 2000GB for the whole month.

    Thanked by 1myhken
  • Seems like this is a risky thing to do on a production server. I think I can live without the extra 700GB.
    Then maybe make a new image on a UEFI VM with a GPT OS disk, then test it on a fresh server at Hetzner to see if it's work. Then maybe replace the OS on my current server after backuping my files.

  • @myhken Open Disk Management, and check for different partitions. If you have more than one partition, then you should have the EFI support partition setup already. If not, I would not suggest trying this on a production machine without having a hot spare.

  • @WSS if you are talking about thees small partitions that I have on my normal Windows 10/7/8.1 installations, I do not have them on my server. So most likely not EFI support.

  • @myhken that is correct. Even if the BIOS supports it, this installation is not necessarily configured to handle it without this partition. It's possible to make work, but not worth the headache for a production system.

    Thanked by 1myhken
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