# Install : ok boot : nok



## mururoa (Jan 13, 2012)

Hi there,

So you picked up a copy of the brand new FreeBSD 9.0 and you performed an install from scratch on one of your computers. All went ok during the install but when you reboot and expect a nice FreeBSD 9.0 boot, your computer just can't boot!

It may, most of the time, and since install itself just worked flawlessly, just be that this particular computer (BIOS) cant boot GPT partitioning. I was in that situation with a computer less that a year old.
The good news is that you just have to install FreeBSD using old MBR partitioning.

That's pretty touchy to do using new bsdinstall but that's just impossible to use bsdinstall if you want a full zfs system too.

I was just on my way to write an howto install FreeBSD 9.0 full zfs with MBR but it appears there is already one: http://daemon-notes.com/articles/install/install-zfs/begin

There you have a good howto explaining in details how to install full zfs with GPT too.

Hope it helps and thanks to the author.


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## Sfynx (Jan 13, 2012)

I have PC's from the MBR era booting from GPT just fine. AFAIK it does not know if that partition scheme is there, it just executes the first sector on the drive (the protective MBR sector as defined by /boot/pmbr), which handles the rest (execution of GPT partition bootcode as defined by /boot/gptboot or /boot/gptzfsboot, which in turn grab /boot/loader or /boot/zfsloader, which finally boot the kernel).

Mind you that I always installed it manually from the fixit shell with the *gpart* commands. Maybe *bsdinstall* is just messing up?


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## kpa (Jan 13, 2012)

> AFAIK it does not know if that partition scheme is there, it just executes the first sector on the drive (the protective MBR sector as defined by /boot/pmbr), which handles the rest



This is how the BIOS should handle the protective MBR on a GPT disk, however some BIOSs are too smart and try to interpret the contents of the slice table and fail if there's something unexpected like an EFI GPT slice that the /boot/pmbr contains.


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## mururoa (Jan 13, 2012)

Well, bsdinstall doesn't even bother to know if your hardware is GPT enabled or not and can't do any better than old installer with zfs.

And yes, some old hardware may be faked by the pmbr of GPT and just boot fine but unfortunatly not all. As I said my hardware is NOT old nor THAT exotic (Intel CPU with Intel chipset) but cant handle boot like that. If your HD is <= 2TB GPT is useless and MBR is safer.

But anyway, zfs being one of the strongest strengths of FreeBSD, I can't understand why it was not even an option in the installer. For myself I never installed a FreeBSD without zfs since FreeBSD 7.x. 8.0 was /boot on UFS and after that full zfs.


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