ZFS: amd64, devd, root file system.

[Joao Barros]

I was looking at how Solaris got support for booting off ZFS and the
patch to GRUB to support it.
Is it feasible for FreeBSD's boot loader? What would be the main
issue: technical or licensing?

On 4/9/07, Pawel Jakub Dawidek <pjd at freebsd.org> wrote:
> On Mon, Apr 09, 2007 at 03:17:23AM +0200, Pawel Jakub Dawidek wrote:
> > 3. It is now possible to have root file system on ZFS. You would still
> >    need UFS for your /boot/ file system.
>
> Let me explain how this suppose to work.
>
> You have ad0 disk. Create one slice covering entire disk:
>
>         # fdisk -BI /dev/ad0
>
> Initialize BSDlabel:
>
>         # bsdlabel -wB /dev/ad0s1
>
> Edit your label and create small (like 256MB-512MB) 'a' partition and
> use the rest for 'd' partition:
>
>         # bsdlabel -e /dev/ad0s1
>
> 'd' partition will be used for ZFS:
>
>         # zpool create tank ad0s1d
>
> Create UFS file system on /dev/ad0s1a and copy /boot/ directory in
> there:
>
>         # newfs /dev/ad0s1a
>         # mount /dev/ad0s1a /mnt/tmp
>         # cp -Rp /boot/* /mnt/tmp/
>
> Note that there is no /boot/ directory on ad0s1a yet. This is one of the
> two possibilities. You now need to create symlink:
>
>         # cd /mnt/tmp
>         # ln -s . boot
>
> From what I checked our loader should handle symlinks just fine.
> This will allow us to mount /dev/ad0s1a on /boot directory and use it as
> usual.
>
> Another option is to:
>
>         # cp -Rp /boot /mnt/tmp/
>
> and in the future mount /dev/ad0s1a on eg. /bootdisk and create symlink:
>
>         # ln -s bootdisk/boot /boot
>
> All in all, you should see your kernel when you do:
>
>         # ls -l /mnt/tmp/boot/kernel
>
> Now don't forget to add zfs_load="YES" to /mnt/tmp/boot/loader.conf.
>
> Ok, you also need to tell your loader where your root file system is.
> You can do it by adding:
>
>         vfs.root.mountfrom="zfs:tank"
>
> to /mnt/tmp/boot/loader.conf or you can create /mnt/tmp/etc/fstab file
> with one entry only:
>
>         tank    /       zfs     rw      0       0
>
> On your ZFS file system, your /etc/fstab should contains the line above
> and:
>
>         /dev/ad0s1a     /boot   ufs     rw      0       0
>
> (and everything else, ie. your swap and other file systems)
>
> --
> Pawel Jakub Dawidek                       http://www.wheel.pl
> pjd at FreeBSD.org                           http://www.FreeBSD.org
> FreeBSD committer                         Am I Evil? Yes, I Am!
>
>


-- 
Joao Barros