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Date:      Thu, 1 Sep 2022 17:20:39 -0700
From:      Dan Mahoney <freebsd@gushi.org>
To:        paul beard <paulbeard@gmail.com>
Cc:        FreeBSD-questions <freebsd-questions@freebsd.org>
Subject:   Re: making a disk/slice bootable
Message-ID:  <A99C0412-FD34-46D6-AB9A-AFC45FB10C10@gushi.org>
In-Reply-To: <07BE254D-7701-47F2-94E3-09ED7229FB2B@gushi.org>
References:  <CAMtcK2r4L3SCba4EZt73=F2=fnBnEPGvEL3GCM_38R8_e5meXg@mail.gmail.com> <07BE254D-7701-47F2-94E3-09ED7229FB2B@gushi.org>

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Fdisk is for old-school partitions (where disks had only 1-4 primary =
partitions, and then subdivided those partitions into "slices" =
(bsdlabel).

I'm pretty sure the command you're looking for is:

gpart bootcode -b /boot/pmbr -p /boot/gptboot -i 1 ada1

In english, this says:

* Stick the "protective master boot record" on the root of the disk =
(/boot/pmbr)
* Write a partition boot label from the file specified...
* to this indexed partition (-i 1)=20
* ...on ada1

=46rom there, you may need to tell the stage 0 loader where to find your =
next bootable partition on the next boot() prompt.

-Dan


> On Sep 1, 2022, at 16:44, Dan Mahoney <freebsd@gushi.org> wrote:
>=20
>=20
>=20
>> On Sep 1, 2022, at 16:41, paul beard <paulbeard@gmail.com> wrote:
>>=20
>> I have been mirroring the virtual disk in a FreeBSD vm for a couple =
of years and the main disk got corrupted. The mirrored disk doesn't =
boot, says it can't find a kernel, so I think I missed out on an =
additional step, writing an MBR or boot sector, perhaps.=20
>>=20
>> The files are all there if I mount them from a VM with FreeBSD.I =
assume there is a way to make a mountable disk bootable.  fdisk and =
gpart are available but it's been a long time since I messed around with =
those.=20
>=20
> Let's start with the obvious: Can you post your disk layout?  Mirrored =
how?  Gmirror/ZFS/Hardware raid/etc?  MBR or Gpart?
>=20
> What commands have you tried thusfar?
>=20
> What does the boot so far look like (i.e. are you hitting the stage 0 =
boot loader, and getting the loader prompt?)
>=20
> More info required, please, but this sounds very fixable.
>=20
> -Dan




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