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For a "new" refurbished PC:

ubuntu@ubuntu:~$ 
ubuntu@ubuntu:~$ sudo dmidecode | grep -A3 '^System Information'
System Information
    Manufacturer: Dell Inc.
    Product Name: OptiPlex 790
    Version: 01
ubuntu@ubuntu:~$ 
ubuntu@ubuntu:~$ sudo fdisk -l | grep Disk
Disk /dev/loop0: 1.93 GiB, 2049204224 bytes, 4002352 sectors
Disk /dev/loop1: 27.9 MiB, 28405760 bytes, 55480 sectors
Disk /dev/loop2: 54.97 MiB, 57614336 bytes, 112528 sectors
Disk /dev/loop3: 240.82 MiB, 252493824 bytes, 493152 sectors
Disk /dev/loop4: 62.9 MiB, 65105920 bytes, 127160 sectors
Disk /dev/loop5: 49.8 MiB, 52203520 bytes, 101960 sectors
Disk /dev/sda: 2.75 TiB, 3000592982016 bytes, 5860533168 sectors
Disk model: ST3000DM001-9YN1
Disklabel type: dos
Disk identifier: 0x5771c34f
ubuntu@ubuntu:~$ 
ubuntu@ubuntu:~$ df -H
Filesystem      Size  Used Avail Use% Mounted on
udev            8.3G     0  8.3G   0% /dev
tmpfs           1.7G  1.6M  1.7G   1% /run
/dev/sr0        2.8G  2.8G     0 100% /cdrom
/dev/loop0      2.1G  2.1G     0 100% /rofs
/cow            8.4G  708M  7.7G   9% /
tmpfs           8.4G   93M  8.3G   2% /dev/shm
tmpfs           5.3M  8.2k  5.3M   1% /run/lock
tmpfs           8.4G     0  8.4G   0% /sys/fs/cgroup
tmpfs           8.4G  541k  8.4G   1% /tmp
tmpfs           1.7G   95k  1.7G   1% /run/user/999
/dev/loop1       29M   29M     0 100% /snap/snapd/7264
/dev/loop2       58M   58M     0 100% /snap/core18/1705
/dev/loop3      253M  253M     0 100% /snap/gnome-3-34-1804/24
/dev/loop4       66M   66M     0 100% /snap/gtk-common-themes/1506
/dev/loop5       53M   53M     0 100% /snap/snap-store/433
ubuntu@ubuntu:~$

the hard drive is 3TB but it's running in legacy mode...

Just looking to avoid any licensing problems. It presents no obstacle to simply format the hard drive for Linux, boot in EFI mode and deal with dual booting at a later point? The license key is indeed printed on the case, but it's undoubtedly OEM and so wouldn't be suitable to run as a VM.

Hence the dual-boot:

gparted

I suppose because it's legacy they could only install windows to part of the HD? Can I just switch it over to EFI??

Thufir
  • 1,808

1 Answers1

1

You'll need to switch to GPT scheme to take full advantage of this HDD's capacity - MBR is limited to 2 TB.

Unfortunately Windows supports GPT only in EFI boot mode. As long as the motherboard has UEFI (and if it's less than 10 years old, it almost certainly does) this should not be a problem.

You can either switch boot mode in UEFI setup (aka BIOS setup) and reinstall Windows or you could try to use mbr2gpt first, then change boot mode and resize partitions.

With MBR it's recommended to install Windows first, then Linux later to save some headaches. But if you're going to switch to EFI boot, the order shouldn't matter.

The reason for this is that with MBR there's a single entry point for the boot process which both Windows and Linux overwrite with their boot code: bootmgr for Windows or GRUB2 for Linux. GRUB2 does support chainloading bootmgr, so if you have GRUB2 in your MBR, you can still boot both OSes. However bootmgr doesn't support Linux, so if you install Windows second, your MBR gets overwritten with bootmgr and you're locked out of Linux.

With EFI boot it's not a problem anymore, as EFI has its built-in boot manager and you can have more than one loader installed - they all live on an EFI System Partition, or ESP for short. It's a small partition, typically between 100-500 MB used just for the purpose of storing loaders. Both Windows and Linux will just install their loaders there (still bootmgr for Windows and usually GRUB2 for Linux, although some distros use systemd-boot) and register them in EFI boot list. You can then reorder this boot list in UEFI setup, so the worst case scenario is that you'd have to move Linux to the top of the list. Much easier than reinstalling GRUB2 into MBR.

gronostaj
  • 58,482