Convert MBR Partitions to GPT

Thomas D. Dean tomdean at
Mon Sep 2 12:04:56 UTC 2019

On 9/2/19 4:39 AM, Polytropon wrote:
> On Sun, 1 Sep 2019 19:47:33 -0700, Thomas D. Dean wrote:
>> I have 5 disk drives, with two (same) OS's.  Actually, two drives have
>> Windows 7 and its secondary plex.  From an earlier post:
>> sata6g_1  HD0 SSD    ubuntu 18.04
>> sata6g_2  HD1 WD5000 Ubuntu 18.04
>> sata3g_3  HD2 WD5000 windows 7 - not used
>> sata3g_4  HD3 WD5000 backup
>> sata3g_5  HD4 WD5000 windows 7 secondary plex- not used
>> sata3g_6  DVD DRW-24B3LT
>> sata6g_E1 (empty)
>> sata6g_E2 (empty)
>> I plan to keep the SSD Ubuntu install until I can get FreeBSD up and
>> running the way I want.
>> So, for now, I want to install FreeBSD on sata3g_5 HD4.
>> My motherboard, ASUS P9X79 PRO has support for UEFI boot.
>> Is it worth the effort to change everything to GPT, or, should I just
>> use GPT on the FreeBSD disk?  I am leaning toward the later, but, ...
>> I think the future has a SSD for FreeBSD.
> Don't confuse UEFI and GPT. :-)
> YOu can use both GPT and MBR (not on the same disk, of course,
> but on different disks). Choosing MBR is suggested today only
> for the few cases where it's absolutely needed. Use GPT if you
> can.
> You cannot "convert" between the two except via "backup, re-init,
> restore", which probably is not what you have in mind.
> But as it is about a new installation of FreeBSD into a multi-OS
> setting, I'd suggest to leave everything untouched, install
> FreeBSD on its disk using GPT partitioning, and add a "chain loader"
> entry to GRUB configuration that boots FreeBSD. GRUB can understand
> both MBR and GPT, so it doesn't matter.

Something, possibly BSDinstall or, maybe something unknown made the 2 
Windows 7 disks unbootable.  Great, now I can use them for something 
other than adding weight to the box.

I changed HD2, sdc to GPT with gparted.  I installed Ubuntu 18.04 on it.
I booted sda and used update-grub2.  Seemed to go OK, but I could not 
get grub to boot sdc.  The boot menu listed sdc, but when selected igrub 
actually booted sda.  Looking at boot/grub/grub.cfg, I see the menuentry 
for sdc to have the same values as sda.

grub bug??

Tom Dean

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