Convert MBR Partitions to GPT

Polytropon freebsd at
Mon Sep 2 12:11:25 UTC 2019

On Mon, 2 Sep 2019 05:04:52 -0700, Thomas D. Dean wrote:
> 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.

Maybe there is just some damage to the bootcode of each "Windows".
Suggestion: Unplug all disks except one of those (one at each time),
boot with a "Windows" installation / repair DVD, restore the boot
sector - should boot fine again.

However, it sounds totally wrong that a FreeBSD installer even
_touches_ disks that are not subject to the FreeBSD installation.
I can image that adding boot code (single-boot or boot manager)
to the 1st disk of a setup is possible, but what you're describing
sounds just wrong. Not entirely impossible, but ...

Also boot into Linux and make sure the GRUB configuration is

> 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??

Something went wrong when update-grub2 altered the configuration,
I'd guess. You can manually change the GRUB configuration as needed.

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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