[OpenIndiana-discuss] 'pkg image-update' and BEs

[Michael Schuster]

Hi Aneurin,

I'd expect one of the design goals of the whole image-update process was to
work with as little interruption as possible (we had this in live upgrade
as well, so the historical precedent is fairly clear, IMO anyway): you
could run your update, watch it finish, analyse logs etc., all while the
machine (think "big server") was up and running *completely unchanged*.
Only when/if you're satisfied that the update did what you expected it to
do, you could (schedule a) reboot. IMO that's a much safer approach than
what you describe.

cheers
Michael

On Mon, Jun 25, 2012 at 4:18 PM, Aneurin Price <aneurin.price at gmail.com>wrote:

> Hi folks,
>
> I have a basic newbie question: can somebody help me to understand how
> exactly the boot environments created by 'pkg image-update' work?
>
> Lets say I start with the BE 'mysystem'. My initial expectation -
> obviously incorrect - was that performing the update would take a
> snapshot (call it 'mysystem-1'), and create a corresponding BE, then
> apply the relevant updates to the *currently active* BE. Then I would
> immediately have access to updates that don't require a restart (new
> application software versions etc.); I can reboot to get the new
> kernel version, or I can reboot and choose the mysystem-1 BE if
> anything went wrong.
>
> In short, I was expecting the operation to be roughly equivalent to
> snapshot creation, followed by 'apt-get dist-upgrade'.
>
> That obviously isn't the case, but I can't find a clear explanation
> anywhere of how the process actually works. From observation it
> appears to be the following: a snapshot and corresponding BE are
> created, and the update process is applied to that *new* BE. Thus
> newly installed updates aren't available until rebooting into that new
> BE. The current BE effectively acts as the 'backup' snapshot, so any
> other changes to the system (applied to the running environment) not
> only won't apply to the new BE, but are basically modifying the
> backup. Hence, updating should be the *very last* thing to do before a
> reboot, and rebooting ASAP after performing the update is *extremely*
> important.
>
> Is that understanding correct?
>
> Assuming so, is it possible to make pkg behave more like my initial
> expectation? I suppose I could create a snapshot myself using beadm,
> then tell pkg not to create a new environment, but is that likely to
> bite me in some nasty way? I'd like a better understanding of why the
> system works the way it does before trying to fight it :P.
>
> Thanks for your time.
>
> (PS: Apologies if this list is inappropriate for basic questions like
> this; let me know if that's the case.)
>
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-- 
Michael Schuster
http://recursiveramblings.wordpress.com/