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

[Aneurin Price]

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.)