Re: make world on a zfs system

On Sun, Sep 27, 2009 at 6:45 PM, krad <kraduk_at_googlemail.com> wrote:
> HI,
>
> I have a pure zfs system at home, and was interested in how most others are
> implementing theirs with regard to the os installation.
>
> Most of the guides I have seen have a zpool eg system made up of
> mirrored/raided vdevs, but they usually install the os on the root zfs fs
> for that pool, and have that in loader.conf
>
> eg
>
> vfs.root.mountfrom="zfs:system"
>
> I have done this slightly differently on my system. I initially installed
> onto /system/root. Therefore my loader.conf has the following line
>
> vfs.root.mountfrom="zfs:system/root"
>
> Nothing special there. However this next bit is the cool bit.
>
> Next time i want to upgrade the os i do one of the following
>
>
> zfs snapshot system/root_at_20090926
>
> # if i want speed
> zfs clone system/root_at_20090926 system/root_20090926
>
> #  or better way but a bit slower (2-3 mins)
> zfs send system/root_at_20090926 | zfs receive system/root_20090926
>
> I tend to use the send and receive, as disk space isn't really an issue and
> I dont like having the dependency that you clones as it makes it more
> complicated to delete old file systems.
>
> Now lets install the new os
>
>
> zfs set mountpoint=legacy system/root_20090926
> mount -t zfs system/root_20090926 /mnt
> sed -i -e "system\/root\"/system\/root_20090926\"/" /mnt/boot/loader.conf
> export DESTDIR=/mnt
> cd /usr/src
> make installkernel && make installworld
> zpool set bootfs=system/root_20090926 system
> mergmaster
> init 6
>
> The system will now boot onto the new filesystem. If there is a problem I
> can just boot in with my rescue usb stick and flip the bootfs flag back and
> bang im back in the old os.
>
> Why not just use snapshots I hear you say. Well if I roll back the os I have
> lost the new stuff I have installed. This is ok in terms of getting the os
> back up. However in terms of getting the new installation fixed this isn't
> much help. This way I can flip flop back and two between the installations.
> This could be ideal for people who want to have a quick look at current
> every now and again. It would be really cool if this type of thing could get
> integrated into the make world scripts.
>
> Before anyone points out I did steal this idea from opensolaris.
>
> Ideally  I need to do is see if I can get something built into beastie, to
> choose the bootfs for the pool. I'm not sure this is viable, as once you
> have started to load the loader, you must have chosen the bootfs. Has anyone
> looked at this already and can they offer any advice?
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I've done this before - but instead of make installword I did
'freebsd-update upgrade -r <version>' instead by chrooting to the new
root environment.

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